WO2018139092A1 - Resonator - Google Patents

Resonator Download PDF

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Publication number
WO2018139092A1
WO2018139092A1 PCT/JP2017/044787 JP2017044787W WO2018139092A1 WO 2018139092 A1 WO2018139092 A1 WO 2018139092A1 JP 2017044787 W JP2017044787 W JP 2017044787W WO 2018139092 A1 WO2018139092 A1 WO 2018139092A1
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WO
WIPO (PCT)
Prior art keywords
magnetization
layer
magnetic field
free layer
magnetization free
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PCT/JP2017/044787
Other languages
French (fr)
Japanese (ja)
Inventor
直通 出川
晋治 原
邦恭 伊藤
実 大田
英嗣 小村
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Tdk株式会社
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Publication of WO2018139092A1 publication Critical patent/WO2018139092A1/en

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
    • G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/82—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by variation of the magnetic field applied to the device
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/22—Constructional features of resonators consisting of magnetostrictive material
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/10—Magnetoresistive devices

Definitions

  • the present invention relates to a resonator using a magnetoresistive effect element.
  • spintronics has attracted attention as a technology that can be applied to high-frequency devices such as high-frequency filters.
  • One technique that has attracted particular attention in spintronics is a technique using ferromagnetic resonance.
  • the magnetization of a ferromagnetic material placed in a magnetic field can oscillate such that the direction of magnetization changes. This magnetization vibration is, for example, precession.
  • Ferromagnetic resonance is a phenomenon in which magnetization is oscillated at a specific frequency and the amplitude of vibration of the magnetization is maximized by applying energy varying at a specific frequency.
  • the frequency of magnetization vibration when the amplitude of magnetization vibration becomes maximum is referred to as a ferromagnetic resonance frequency.
  • Examples of energy that generates ferromagnetic resonance include a high-frequency magnetic field and a high-frequency current.
  • spintronic element an element using spintronics is referred to as a spintronic element.
  • a magnetoresistive element including a magnetization fixed layer, a magnetization free layer whose magnetization direction changes, and a spacer layer disposed between the magnetization fixed layer and the magnetization free layer.
  • Patent Document 1 discloses a frequency conversion element including a magnetoresistive effect element, a mechanism for applying a magnetic field to the frequency conversion element, a local oscillator for applying a local oscillation signal to the frequency conversion element, a frequency conversion element, A frequency conversion device that is electrically connected and has an input terminal for inputting an external input signal is described.
  • the magnetization free layer of the magnetoresistive effect element can cause ferromagnetic resonance, there is a possibility that a resonator using the magnetoresistive effect element can be realized.
  • a resonator using the magnetoresistive effect element use a phenomenon in which the resistance value of the magnetoresistive effect element changes in accordance with the magnetization oscillation of the magnetization free layer such that the magnetization direction of the magnetization free layer changes. It is possible.
  • the present invention has been made in view of such problems, and an object thereof is to provide a practical resonator using a magnetoresistive effect element.
  • the resonator of the present invention includes a magnetoresistive effect element, an external magnetic field application unit, and an energy application unit.
  • the magnetoresistive effect element includes at least a magnetization fixed layer made of a first magnetic layer, a magnetization free layer having magnetization whose direction changes, and is disposed between the magnetization fixed layer and the magnetization free layer and is attached to the first magnetic layer. And a spacer layer in contact therewith.
  • the first magnetic layer has magnetization in the first direction.
  • the external magnetic field application unit applies an external magnetic field, which is a static magnetic field in the second direction, to the magnetization free layer of the magnetoresistive effect element.
  • the energy applying unit applies energy for vibrating the magnetization of the magnetization free layer to the magnetoresistive effect element.
  • the angle formed by the second direction with respect to the first direction is in the range of 90 ° to 150 °.
  • the energy applying unit may apply a high frequency current to the magnetoresistive effect element as the energy.
  • an energy provision part may provide a high frequency magnetic field to a magnetoresistive effect element as the said energy.
  • the angle formed by the second direction with respect to the first direction may be in the range of 105 ° to 135 °.
  • At least one of the first direction and the second direction may be a direction intersecting with the interface between the magnetization free layer and the spacer layer.
  • the second direction may be a direction perpendicular to the interface between the magnetization free layer and the spacer layer.
  • the second direction may be a direction parallel to the interface between the magnetization free layer and the spacer layer.
  • the first direction may be a direction perpendicular to the interface between the magnetization fixed layer and the spacer layer.
  • the first direction may be a direction parallel to the interface between the magnetization fixed layer and the spacer layer.
  • the external magnetic field application unit may be capable of changing the magnitude of the external magnetic field. Further, the external magnetic field application unit may be capable of changing the second direction.
  • the resonator of the present invention may further include an output port where a high frequency output signal resulting from the vibration of magnetization of the magnetization free layer appears.
  • ferromagnetic resonance can be caused in the magnetization free layer by applying energy varying at a frequency equal to the ferromagnetic resonance frequency of the magnetization free layer of the magnetoresistive effect element to the magnetoresistive effect element. it can.
  • the angle formed by the second direction with respect to the first direction is an angle within the range of 90 ° to 150 °.
  • the resonator 1 includes a magnetoresistive effect element 2, an external magnetic field application unit 3, and an energy application unit 4.
  • the magnetoresistive effect element 2 is disposed between the magnetization fixed layer 21 having at least a first magnetic layer, a magnetization free layer 23 having magnetization whose direction changes, and between the magnetization fixed layer 21 and the magnetization free layer 23 and And a spacer layer 22 in contact with one magnetic layer.
  • the first magnetic layer has magnetization in the first direction.
  • the first magnetic layer has a property that the magnetization direction is less likely to change and the coercive force is larger than that of the magnetization free layer 23. Therefore, the first direction, which is the magnetization direction of the first magnetic layer, is less likely to change than the magnetization direction of the magnetization free layer 23.
  • the first direction may be substantially or completely fixed.
  • the magnetization fixed layer 21 may be composed of only the first magnetic layer, or may include other layers in addition to the first magnetic layer. In the present embodiment, the case where the magnetization fixed layer 21 includes only the first magnetic layer will be described. In the present embodiment, the first direction, which is the magnetization direction of the first magnetic layer, is also the magnetization direction of the magnetization fixed layer 21. An example in which the magnetization fixed layer 21 includes a plurality of layers including the first magnetic layer will be described in a third embodiment described later.
  • the magnetoresistive effect element 2 has a first end face 2a and a second end face 2b located at both ends in the stacking direction of a plurality of layers constituting the magnetoresistive effect element 2.
  • the magnetization fixed layer 21, the spacer layer 22, and the magnetization free layer 23 are laminated in this order from the second end face 2b side.
  • the external magnetic field application unit 3 applies an external magnetic field that is a static magnetic field in the second direction to the magnetization free layer 23.
  • the configuration of the external magnetic field application unit 3 and the first and second directions will be described in detail later.
  • the effective magnetic field acting on the magnetization of the magnetization free layer 23 is a combination of all kinds of magnetic fields acting on the magnetization of the magnetization free layer 23.
  • the magnetic field acting on the magnetization of the magnetization free layer 23 includes a magnetic anisotropic magnetic field, an exchange magnetic field, a demagnetizing field, and the like.
  • the direction of the effective magnetic field acting on the magnetization of the magnetization free layer 23 matches or substantially matches the second direction that is the direction of the external magnetic field.
  • the energy applying unit 4 applies energy for vibrating the magnetization of the magnetization free layer 23 to the magnetoresistive effect element 2.
  • a high frequency current is used as the energy.
  • the energy applying unit 4 is configured to apply a high frequency current to the magnetoresistive effect element 2 as energy. More specifically, the energy applying unit 4 includes a first input port 5 to which a high frequency input signal is applied and a high frequency current based on the high frequency input signal applied to the input port 5 to the magnetoresistive element 2.
  • a high frequency input signal is a signal which has a frequency of 100 MHz or more, for example. The frequency of the high frequency current is equal to the frequency of the high frequency input signal.
  • the resonator 1 further includes an output port 8 and a second signal line 7.
  • the magnetoresistive effect element 2 generates a high frequency output signal resulting from the vibration of magnetization of the magnetization free layer 23.
  • the second signal line 7 transmits this high frequency output signal from the magnetoresistive effect element 2 to the output port 8. This high frequency output signal appears at the output port 8.
  • the magnetoresistive element 2 is located between the input port 5 and the output port 8.
  • the resonator 1 further includes a first electrode 11, a second electrode 12, and a ground electrode 13.
  • the first electrode 11 and the second electrode 12 are provided such that the magnetoresistive element 2 is interposed therebetween.
  • the first electrode 11 and the second electrode 12 are used for flowing a high-frequency current and a direct current described later to the magnetoresistive effect element 2.
  • the first electrode 11 is in contact with the first end face 2 a of the magnetoresistive effect element 2.
  • the second electrode 12 is in contact with the second end face 2 b of the magnetoresistive effect element 2.
  • the direct current flows in a direction intersecting the surface of each layer constituting the magnetoresistive effect element 2, for example, in a direction perpendicular to the surface of each layer constituting the magnetoresistive effect element 2.
  • the input port 5 has a pair of terminals 51 and 52.
  • One end of the first signal line 6 is electrically connected to the terminal 51.
  • the other end of the first signal line 6 is electrically connected to the first electrode 11.
  • the output port 8 has a pair of terminals 81 and 82. One end of the second signal line 7 is electrically connected to the terminal 81. The other end of the second signal line 7 is electrically connected to the second electrode 12.
  • the terminal 52 of the input port 5 and the terminal 82 of the output port 8 are each electrically connected to the ground electrode 13.
  • the potential of the ground electrode 13 is used as a reference potential.
  • the first and second electrodes 11 and 12 may be composed of a single layer film made of any one of Al, Ta, Cu, Au, AuCu, and Ru, for example. You may be comprised by the laminated body of the some film
  • the signal lines 6 and 7 and the ground electrode 13 may be configured by a microstrip line or a coplanar waveguide.
  • the resonator 1 further includes a choke coil 14 and a DC input terminal 15.
  • One end of the choke coil 14 is electrically connected to the second signal line 7.
  • the other end of the choke coil 14 is electrically connected to the ground electrode 13.
  • the DC input terminal 15 is electrically connected to the first signal line 6.
  • the magnetoresistive element 2 is located between the DC input terminal 15 and the choke coil 14. A direct current is input to the direct current input terminal 15, and this direct current is supplied to the magnetoresistive element 2.
  • the choke coil 14 has an inductance. Thereby, the impedance of the choke coil 14 increases as the frequency of the current passing through the choke coil 14 increases. Therefore, the choke coil 14 allows a direct current passing through the second signal line 7 to pass through the ground electrode 13 and exhibits a high impedance to a high-frequency output signal passing through the second signal line 7.
  • the choke coil 14 for example, a chip inductor or a line is used.
  • the inductance of the choke coil 14 is preferably 10 nH or more.
  • the resonator 1 may include a resistance element having an inductance component instead of the choke coil 14.
  • a DC current source 16 is provided between the DC input terminal 15 and the ground electrode 13 as shown in FIG.
  • a closed circuit including the DC current source 16, the DC input terminal 15, the first signal line 6, the magnetoresistive effect element 2, the second signal line 7, the choke coil 14, and the ground electrode 13 is formed.
  • the direct current source 16 generates a direct current flowing through this closed circuit.
  • a direct current flows in a direction from the magnetization free layer 23 toward the magnetization fixed layer 21.
  • the DC current source 16 is configured by a circuit combining a DC voltage source and a resistor, for example.
  • a variable resistor or a fixed resistor is used as the resistor.
  • the magnitude of the direct current can be changed.
  • the direct current becomes a constant value.
  • a resistance element having a choke coil or an inductance component between the DC input terminal 15 and the DC current source 16 is used. May be provided.
  • a DC voltage source may be provided between the DC input terminal 15 and the ground electrode 13.
  • the DC voltage source generates a DC voltage applied to the magnetoresistive effect element 2.
  • the DC voltage source and the magnetoresistive effect element 2 are connected so that a DC voltage is applied to the magnetoresistive effect element 2 so that the magnetization free layer 23 has a higher potential than the magnetization fixed layer 21.
  • a direct current flows in a direction from the magnetization free layer 23 toward the magnetization fixed layer 21.
  • the DC voltage source may be capable of generating a constant DC voltage, or may be capable of changing the magnitude of the generated DC voltage.
  • the direct current means a current whose direction does not change with time.
  • the direct current includes a current whose magnitude does not change with time and a current whose magnitude changes with time.
  • the DC voltage refers to a voltage whose direction does not change with time.
  • the DC voltage includes a voltage whose magnitude does not change with time and a voltage whose magnitude changes with time.
  • the ground electrode 13 may be external to the resonator 1.
  • the resonator 1 is used with the terminal 52 of the input port 5, the terminal 82 of the output port 8, and the other end of the choke coil 14 electrically connected to the ground electrode 13.
  • the magnetoresistive effect element 2 will be described in more detail.
  • the magnetoresistive effect is manifested by the interaction between the magnetization of the magnetization fixed layer 21 and the magnetization of the magnetization free layer 23. Specifically, as the angle formed by the magnetization direction of the magnetization free layer 23 with respect to the magnetization direction of the magnetization fixed layer 21 approaches from 0 ° to 180 °, the resistance value of the magnetoresistive effect element 2 increases.
  • the magnetization fixed layer 21 is made of a ferromagnetic material.
  • a ferromagnetic material constituting the magnetization fixed layer 21 for example, a high spin polarizability material such as Fe, Co, Ni, NiFe, FeCo, FeCoB, or a Heusler alloy is used.
  • the thickness of the magnetization fixed layer 21 is preferably in the range of 1 to 10 nm.
  • the magnetoresistive effect element 2 may further include an antiferromagnetic layer for fixing the magnetization direction of the magnetization fixed layer 21.
  • the antiferromagnetic layer is provided so as to be in contact with a surface of the magnetization fixed layer 21 opposite to the surface in contact with the spacer layer 22.
  • the antiferromagnetic layer fixes the magnetization direction of the magnetization fixed layer 21 by exchange coupling with the magnetization fixed layer 21.
  • the material of the antiferromagnetic layer for example, any of FeO, CoO, NiO, CuFeS 2 , IrMn, FeMn, PtMn, Cr, and Mn is used.
  • the magnetization direction of the magnetization fixed layer 21 may be fixed by magnetic anisotropy based on the crystal structure, shape, etc. without using the antiferromagnetic layer.
  • An example in which the magnetoresistive element 2 includes an antiferromagnetic layer will be described in a third embodiment described later.
  • the entire spacer layer 22 may be made of a nonmagnetic material.
  • the nonmagnetic material constituting the spacer layer 22 may be a conductive material, an insulating material, or a semiconductor material.
  • Examples of the nonmagnetic conductive material constituting the spacer layer 22 include Cu, Ag, Au, and Ru.
  • Examples of the nonmagnetic insulating material constituting the spacer layer 22 include Al 2 O 3 and MgO.
  • the thickness of the spacer layer 22 is preferably in the range of 0.5 to 3.0 nm.
  • nonmagnetic semiconductor material constituting the spacer layer 22 examples include an oxide semiconductor containing one or more of Zn, In, Sn, and Ga.
  • the thickness of the spacer layer 22 is preferably in the range of 1.0 to 4.0 nm.
  • the spacer layer 22 may include an insulating portion made of an insulating material and one or more energization portions made of a conductive material and provided in the insulating portion.
  • the insulating material constituting the insulating portion include Al 2 O 3 and MgO.
  • the conductive material constituting the energizing portion include CoFe, CoFeB, CoFeSi, CoMnGe, CoMnSi, CoMnAl, Fe, Co, Au, Cu, Al, and Mg.
  • the thickness of the spacer layer 22 is preferably in the range of 0.5 to 2.0 nm.
  • the magnetization free layer 23 is made of a ferromagnetic material.
  • the magnetization free layer 23 in the present embodiment preferably has an easy axis of magnetization in a direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22.
  • Such a magnetization free layer 23 is made of, for example, a film made of Co, a CoCr alloy, a CoCrPt alloy, a FePt alloy, a rare earth-containing SmCo alloy, a TbFeCo alloy, or a Heusler alloy, or a Co multilayer film. Can do.
  • the thickness of the magnetization free layer 23 is preferably in the range of 1 to 10 nm.
  • the magnetoresistive effect element 2 may further include first and second metal layers.
  • the first metal layer is provided between the magnetization free layer 23 and the first electrode 11.
  • the second metal layer is provided between the magnetization fixed layer 21 and the second electrode 12.
  • the first metal layer is used as a cap layer.
  • the second metal layer is used as a seed layer or a buffer layer.
  • the first and second metal layers are composed of, for example, a single layer film or a multilayer film including one or more of Ru, Ta, Cu, and Cr.
  • the thickness of the first and second metal layers is preferably in the range of 2 to 10 nm.
  • the external magnetic field application unit 3 is disposed in the vicinity of the magnetoresistive element 2.
  • the external magnetic field application unit 3 includes an electromagnet. More specifically, the external magnetic field application unit 3 includes a core part 32 made of a magnetic material and a coil 31 wound around the core part 32. The core part 32 and the coil 31 constitute an electromagnet.
  • the magnetoresistive effect element 2 and the core portion 32 are arranged so as to be aligned in a direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22. Particularly in the present embodiment, the core portion 32 is disposed so as to face the first end face 2 a of the magnetoresistive element 2.
  • the external magnetic field application unit 3 further includes a first yoke 33 and a second yoke 34 made of a magnetic material.
  • the first yoke 33 is connected to the end surface of the core portion 32 opposite to the magnetoresistive effect element 2.
  • the second yoke 34 is disposed so as to face the end surface of the core portion 32 on the magnetoresistive effect element 2 side.
  • the magnetoresistive element 2 is disposed between the core portion 32 and the second yoke 34.
  • the first yoke 33 and the second yoke 34 may be connected via a third yoke (not shown) made of a magnetic material.
  • the external magnetic field application unit 3 is configured to be able to change the magnitude of the external magnetic field.
  • the magnitude of the external magnetic field can be changed by adjusting the magnitude of the current flowing through the coil 31.
  • the range of the magnitude of the external magnetic field that can be changed by the external magnetic field application unit 3 is, for example, 0 to 2 kOe (1Oe is 79.6 A / m).
  • the second direction which is the direction of the external magnetic field, can be switched between the direction from the core portion 32 toward the magnetoresistive effect element 2 and the opposite direction by changing the direction of the current flowing through the coil 31. it can.
  • the first direction which is the direction of magnetization of the magnetization fixed layer 21 is represented by the symbol D1
  • the second direction which is the direction of the external magnetic field applied to the magnetization free layer 23 is represented by the symbol D2
  • the magnetization The direction of magnetization of the free layer 23 is represented by the symbol D3.
  • FIG. 2 shows the magnetoresistive element 2 and the first to third directions D1, D2, and D3.
  • FIG. 3 shows an angle formed by the second direction D2 with respect to the first direction D1.
  • the X direction, the Y direction, and the Z direction are defined.
  • the X direction, the Y direction, and the Z direction are orthogonal to each other.
  • one direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 is defined as the Z direction.
  • Both the X direction and the Y direction are parallel to the interface.
  • the X direction is a direction toward the right side
  • the Y direction is a direction from the near side to the back side in FIG.
  • FIG. 3 also shows the X, Y, and Z directions shown in FIG.
  • the second direction D2 of the first direction D1 and the second direction D2 is a direction intersecting the interface between the magnetization free layer 23 and the spacer layer 22.
  • the second direction D2 is a direction perpendicular to the interface and coincides with the Z direction.
  • the magnetoresistive effect element 2 and the core portion 32 (see FIG. 1) of the external magnetic field application unit 3 are arranged in the Z direction.
  • FIG. 2 shows a state in which the magnetization direction D3 of the magnetization free layer 23 coincides with the second direction D2 (Z direction).
  • the angle formed by the second direction D2 with respect to the first direction D1 is represented by the symbol ⁇ .
  • the angle ⁇ is in the range of 90 ° to 150 °.
  • the angle ⁇ is preferably in the range of 105 ° to 135 °.
  • the first direction D1 is a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22.
  • the angle ⁇ is greater than 90 ° and equal to or less than 150 °
  • the first direction D1 is a direction intersecting the interface between the magnetization free layer 23 and the spacer layer 22.
  • the first direction D1 can be easily set to an arbitrary direction, for example, by changing the direction of the magnetic field when setting the magnetization direction of the magnetization fixed layer 21 by heat treatment in a magnetic field.
  • the second direction D2 is a direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22. Thereby, the external magnetic field in the second direction D2 can be easily and accurately applied to the magnetization free layer 23.
  • a high-frequency current is used as the energy.
  • the high frequency current is superimposed on the direct current flowing through the magnetoresistive effect element 2 and applied to the magnetoresistive effect element 2.
  • the current density in the magnetization free layer 23 changes with the frequency of the high-frequency current, and as a result, the spin transfer torque that acts on the magnetization of the magnetization free layer 23 causes the high-frequency current to Varies with frequency.
  • Spin transfer torque refers to the magnetization of a ferromagnet so that the magnetization of the ferromagnet rotates in the direction opposite to the change of the spin angular momentum in the change of the spin current in the ferromagnet in which the inflow or outflow of the spin current occurs. Is the torque acting on the. Therefore, in the magnetization free layer 23, when the spin transfer torque changes at the frequency of the high frequency current, the magnetization of the magnetization free layer 23 oscillates at the frequency of the high frequency current so that its direction changes.
  • the magnetoresistive effect element 2 generates a high frequency output signal resulting from the vibration of magnetization of the magnetization free layer 23.
  • the frequency of the high frequency output signal is equal to the frequency of the high frequency input signal.
  • the high frequency output signal is transmitted from the magnetoresistive effect element 2 to the output port 8 by the second signal line 7. This high frequency output signal appears at the output port 8.
  • the magnetoresistance The resistance value of the effect element 2 changes.
  • a high frequency output signal is generated by a change in the resistance value of the magnetoresistive element 2.
  • the high-frequency output signal appears as a change in the potential of the terminal 81 of the output port 8.
  • the frequency of the high frequency input signal is equal to the ferromagnetic resonance frequency of the magnetization free layer 23
  • ferromagnetic resonance occurs in the magnetization free layer 23
  • the amplitude of magnetization vibration of the magnetization free layer 23 is maximized.
  • the amplitude of the high frequency output signal is also maximized.
  • the ferromagnetic resonance frequency of the magnetization free layer 23 can be changed by changing the magnitude of the effective magnetic field acting on the magnetization free layer 23, for example.
  • the magnitude of the effective magnetic field acting on the magnetization free layer 23 depends on the magnitude of the external magnetic field applied to the magnetization free layer 23 by the external magnetic field application unit 3. Therefore, in the present embodiment, the ferromagnetic resonance frequency of the magnetization free layer 23 can be changed, for example, by changing the magnitude of the external magnetic field applied to the magnetization free layer 23. More specifically, the ferromagnetic resonance frequency increases when the external magnetic field is increased.
  • the angle ⁇ formed by the second direction D2 with respect to the first direction D1 is an angle in the range of 90 ° to 150 °.
  • the resistance value of the magnetoresistive effect element 2 in a state where the first direction D1 which is the magnetization direction of the magnetization fixed layer 21 and the magnetization direction D3 of the magnetization free layer 23 coincide with each other is Rp, and the magnetization free layer
  • the maximum value of the change amount of the resistance value of the magnetoresistive effect element 2 due to the magnetization vibration of 23 is ⁇ R
  • the rate of change in resistance of the magnetoresistive effect element 2 due to the magnetization vibration of the magnetization free layer 23 is ⁇ R / Rp It is defined as The resistance change rate ⁇ R / Rp is proportional to ⁇ R.
  • the relationship between the angle ⁇ and the resistance change rate ⁇ R / Rp when a high-frequency current based on a high-frequency input signal having a frequency equal to the ferromagnetic resonance frequency of the magnetization free layer 23 is applied to the magnetoresistive effect element 2 was obtained.
  • the ferromagnetic resonance frequency of the magnetization free layer 23 and the frequency of the high frequency input signal were changed within the range of 0.3 GHz to 2.8 GHz.
  • the ferromagnetic resonance frequency of the magnetization free layer 23 was changed by adjusting the magnitude of the effective magnetic field acting on the magnetization free layer 23.
  • Figure 4 shows the simulation results.
  • the horizontal axis represents the angle ⁇
  • the vertical axis represents the resistance change rate ⁇ R / Rp.
  • FIG. 4 shows that the resistance change rate ⁇ R / Rp has the following dependence on the angle ⁇ .
  • the resistance change rate ⁇ R / Rp becomes maximum when the angle ⁇ is 120 ° or an angle in the vicinity thereof.
  • the resistance change rate ⁇ R / Rp is relatively large when the angle ⁇ is in the range of approximately 90 ° to 150 °, compared to when the angle ⁇ is out of the range.
  • the resistance change rate ⁇ R / Rp is relatively remarkably increased when the angle ⁇ is in the range of about 105 ° to 135 °, compared to the case where the angle ⁇ is out of the range.
  • ⁇ R corresponds to the amount of change in the resistance value of the magnetoresistive element 2 when ferromagnetic resonance is caused in the magnetization free layer 23.
  • the angle ⁇ is preferably in the range of 90 ° to 150 °, and more preferably in the range of 105 ° to 135 °. Therefore, in the present embodiment, the angle ⁇ is set to an angle within the range of 90 ° to 150 °, preferably within the range of 105 ° to 135 °.
  • FIG. 5 shows an example of the pass characteristic of the resonator 1 when the angle ⁇ is 120 °.
  • the pass characteristic of the resonator 1 is expressed using an S parameter S21 that represents the ratio of the power of the high-frequency output signal to the power of the high-frequency input signal.
  • the horizontal axis indicates the frequency
  • the vertical axis indicates the S parameter S21 expressed in dB.
  • the value of the S parameter S21 expressed in dB is expressed as -Id, the smaller the value of I, the larger the ratio of the power of the high frequency output signal to the power of the high frequency input signal.
  • the ferromagnetic resonance frequency of the magnetization free layer 23 is set to 3.07 GHz.
  • FIG. 5 shows that the value of I is the smallest when the frequency of the high-frequency input signal is equal to the ferromagnetic resonance frequency of the magnetization free layer 23.
  • FIG. 5 shows that the resonator 1 has a sufficiently practical resonator function.
  • the ferromagnetic resonance frequency of the magnetization free layer 23 corresponds to the resonance frequency of the resonator 1.
  • the ferromagnetic resonance frequency of the magnetization free layer 23 corresponding to the resonance frequency of the resonator 1 can be changed by changing the magnitude of the external magnetic field applied to the magnetization free layer 23. . Therefore, the resonator 1 according to the present embodiment can be used for a plurality of applications having different resonance frequencies.
  • the magnetization behavior of the magnetization free layer 23 will be described with reference to FIG.
  • the magnetization of the magnetization fixed layer 21 is represented by the symbol M 1
  • the magnetization of the magnetization free layer 23 is represented by the symbol M 2
  • the effective magnetic field acting on the magnetization M 2 of the magnetization free layer 23 is represented by the symbol H eff .
  • FIG. 6 shows the directions of the magnetizations M 1 and M 2 and the effective magnetic field H eff .
  • the behavior of the magnetization M 2 of the magnetization free layer 23 is expressed by the following formula (1) using an LLG (Landau Lifshitz Gilbert) equation.
  • the first term, the second term, and the third term of Equation (1) represent precession torque, damping torque, and spin transfer torque, respectively.
  • the arrow with the symbol T1 represents the precession torque
  • the arrow with the symbol T2 represents the damping torque
  • the arrow with the symbol T3 represents the spin transfer torque.
  • M 1, m 2 in the formula (1) is a unit vector in the direction of the magnetization M 1, M 2.
  • ⁇ is a gyro magnetic constant
  • ⁇ is a damping constant
  • I e is a current density.
  • ⁇ is a value obtained by dividing the Dirac constant, that is, the converted Planck constant by 2e (e is electric charge).
  • G is a parameter representing the efficiency of spin transfer. g is expressed by the following formula (2) using the spin polarizability P and the angle ⁇ (see FIG. 6) formed by the direction of the magnetization M 2 with respect to the direction of the magnetization M 1 .
  • FIG. 7 is a characteristic diagram showing changes in g ⁇ sin ⁇ when the angle ⁇ is changed.
  • the horizontal axis indicates the angle ⁇
  • the vertical axis indicates the value of g ⁇ sin ⁇ .
  • the curves denoted by reference numerals 91, 92, 93, and 94 indicate g ⁇ sin ⁇ when the spin polarizability P is 0.4, 0.5, 0.6, and 0.7, respectively. Yes.
  • the practical spin polarizability P is, for example, in the range of 0.5 to 0.7. From FIG.
  • the direction of the effective magnetic field H eff coincides with or substantially coincides with the second direction D2, which is the direction of the external magnetic field.
  • direction D3 of the magnetization M 2 of the magnetization free layer 23 is in the state to match the second direction D2, the direction D3 of the magnetization M 2 of the magnetization free layer 23 coincides with the direction of the effective magnetic field H eff, approximately Match.
  • the angle ⁇ shown in FIG. 6 matches or substantially matches the angle ⁇ shown in FIG. Therefore, in this state, the spin transfer torque acting on the magnetization M 2 of the magnetization free layer 23 is maximized when the angle ⁇ is in the range of approximately 105 ° to 120 °.
  • a direct current is supplied to the magnetoresistive effect element 2, and a spin flow from the magnetization fixed layer 21 to the magnetization free layer 23 is generated by this direct current.
  • the spin current caused by the direct current gives a spin transfer torque that reduces the angle ⁇ shown in FIG. 6 to the magnetization M 2 of the magnetization free layer 23.
  • this spin transfer torque is referred to as direct current-induced spin transfer torque.
  • the angle formed by the central axis of the vibration of the magnetization M 2 of the magnetization free layer 23 with respect to the direction of the magnetization M 1 of the magnetization fixed layer 21, that is, the first direction D 1 is represented by the symbol ⁇ c.
  • the angle ⁇ formed by the second direction D2 with respect to the first direction D1 is smaller than 180 ° as in the present embodiment, the direct current-induced spin transfer torque acts on the magnetization M 2 of the magnetization free layer 23.
  • the angle ⁇ c is somewhat smaller than the angle formed by the direction of the effective magnetic field H eff with respect to the first direction D1.
  • the direction of the effective magnetic field H eff coincides with or substantially coincides with the second direction D2, which is the direction of the external magnetic field. Therefore, in the present embodiment, the angle ⁇ c is somewhat smaller than the angle ⁇ shown in FIG.
  • the resistance change rate ⁇ R / Rp becomes maximum when the angle ⁇ c is 90 °.
  • the angle ⁇ c is smaller than 90 °.
  • the resistance change rate ⁇ R / Rp can be increased by making the angle ⁇ c close to 90 °.
  • the angle ⁇ is preferably greater than 90 ° and equal to or less than 150 °, and is 105 ° to More preferably, it is within the range of 135 °.
  • a unit vector in the same direction as the first direction D1 is defined as a first unit vector
  • a unit vector in the same direction as the second direction D2 is defined as a second unit vector.
  • a plane perpendicular to or parallel to the interface between the magnetization free layer 23 and the spacer layer 22, and the angle formed by the component of the second unit vector and the component of the first unit vector in the plane is 90
  • a reference plane is preferably parallel to the first direction D1 and the second direction D2.
  • the angle formed by the component of the second unit vector on the reference plane with respect to the component of the first unit vector is equal to the angle ⁇ .
  • at least the XZ plane perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 corresponds to the reference plane.
  • the resonator 1 according to the present embodiment includes an external magnetic field application unit 103 instead of the external magnetic field application unit 3 in the first embodiment.
  • the external magnetic field application unit 103 is disposed in the vicinity of the magnetoresistive element 2.
  • External magnetic field application unit 103 includes first and second electromagnets. More specifically, the external magnetic field application unit 103 includes a first core unit 132 and a second core unit 133 each made of a magnetic material, and a conducting wire 131.
  • the conductive wire 131 includes a first winding portion wound around the first core portion 132 and a second winding portion wound around the second core portion 133. The first winding portion and the second winding portion are connected in series.
  • the first core portion 132 and the first winding portion constitute a first electromagnet.
  • the second core portion 133 and the second winding portion constitute a second electromagnet.
  • the first and second core portions 132 and 133 are arranged on both sides of the magnetoresistive element 2 in a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 of the magnetoresistive element 2.
  • the external magnetic field application unit 103 applies an external magnetic field in the second direction D2 to the magnetization free layer 23 of the magnetoresistive effect element 2.
  • the external magnetic field application unit 103 is configured to be able to change the magnitude of the external magnetic field.
  • the magnitude of the external magnetic field can be changed by adjusting the magnitude of the current flowing through the conducting wire 131.
  • the second direction D2 can be switched between the direction from the core part 132 toward the core part 133 and the opposite direction by changing the direction of the current flowing through the conducting wire 131.
  • the magnetization fixed layer 21 is composed of only the first magnetic layer having the magnetization in the first direction D1.
  • a first example and a second example of the first and second directions D1 and D2 in the present embodiment will be described.
  • FIG. 9 also shows the X, Y, and Z directions shown in FIG. 2 in the first embodiment.
  • the Y direction is the direction from the near side to the back side in FIG.
  • the second direction D2 is a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 and coincides with the X direction.
  • the core part 132, the magnetoresistive effect element 2, and the core part 133 are arranged so as to be aligned in the X direction.
  • FIG. 9 shows a state in which the magnetization direction D3 of the magnetization free layer 23 coincides with the second direction D2 (X direction).
  • the first direction D1 is a direction intersecting the interface between the magnetization free layer 23 and the spacer layer 22.
  • the range of the angle ⁇ formed by the second direction D2 with respect to the first direction D1 is the same as that in the first embodiment.
  • at least the XZ plane perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 corresponds to the reference plane defined in the first embodiment.
  • FIG. 10 also shows X, Y, and Z directions.
  • the second direction D2 is a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 as in the first example, and coincides with the X direction.
  • FIG. 10 shows a state in which the magnetization direction D3 of the magnetization free layer 23 coincides with the second direction D2 (X direction).
  • the first direction D ⁇ b> 1 is also a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22.
  • the range of the angle ⁇ formed by the second direction D2 with respect to the first direction D1 is the same as that in the first embodiment.
  • the XY plane parallel to the interface between the magnetization free layer 23 and the spacer layer 22 corresponds to the reference plane defined in the first embodiment.
  • the magnetization free layer 23 preferably has an easy axis of magnetization in a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22.
  • a magnetization free layer 23 can be constituted by a film made of, for example, CoFe, CoFeB, CoFeSi, CoMnGe, CoMnSi, CoMnAl, or Heusler alloy. The thickness of this film is preferably in the range of 1 to 10 nm.
  • the magnetization free layer 23 in the present embodiment may be composed of a plurality of layers.
  • the layer closest to the spacer layer 22 among the plurality of layers is preferably a high spin polarizability layer having a higher spin polarizability than one or more other layers.
  • the rate of change in resistance of the magnetoresistive effect element 2 can be increased.
  • a material of the high spin polarizability layer a high spin polarizability material such as a CoFe alloy or a CoFeB alloy is used.
  • the thickness of the high spin polarizability layer is preferably in the range of 0.2 to 1.0 nm.
  • the configuration of the resonator 1 according to the present embodiment will be described with reference to FIG.
  • the configuration of the resonator 1 according to the present embodiment is different from that of the first embodiment in the following points.
  • the resonator 1 according to the present embodiment includes an external magnetic field application unit 203 instead of the external magnetic field application unit 3 in the first embodiment.
  • the external magnetic field application unit 203 is disposed in the vicinity of the magnetoresistive element 2.
  • the external magnetic field application unit 203 includes first to fourth electromagnets. More specifically, the external magnetic field application unit 203 includes a first core unit 233, a second core unit 234, a third core unit 235, a fourth core unit 236, and a first core unit 233 each made of a magnetic material. It has a conducting wire 231 and a second conducting wire 232.
  • the first conductive wire 231 includes a first winding part wound around the first core part 233 and a second winding part wound around the second core part 234. The first winding portion and the second winding portion are connected in series.
  • the first core portion 233 and the first winding portion constitute a first electromagnet.
  • the second core portion 234 and the second winding portion constitute a second electromagnet.
  • the second conductive wire 232 includes a third winding portion wound around the third core portion 235 and a fourth winding portion wound around the fourth core portion 236.
  • the third winding portion and the fourth winding portion are connected in series.
  • the third core portion 235 and the third winding portion constitute a third electromagnet.
  • the fourth core portion 236 and the fourth winding portion constitute a fourth electromagnet.
  • the first and second core portions 233 and 234 are disposed on both sides of the magnetoresistive element 2 in the direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 of the magnetoresistive element 2.
  • the third and fourth core portions 235 and 236 are disposed on both sides of the magnetoresistive element 2 in the direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 of the magnetoresistive element 2.
  • the external magnetic field application unit 203 applies an external magnetic field in the second direction D2 to the magnetization free layer 23 of the magnetoresistive element 2.
  • the magnetization fixed layer 21 includes at least a first magnetic layer having magnetization in the first direction D1.
  • the external magnetic field application unit 203 is configured to be able to change both the magnitude of the external magnetic field and the second direction D2, which is the direction of the external magnetic field. This will be described in detail below.
  • the first and second electromagnets apply a magnetic field in a direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 to the magnetization free layer 23.
  • this magnetic field is referred to as a vertical component of the external magnetic field.
  • the magnitude of the vertical component of the external magnetic field can be changed by adjusting the magnitude of the current flowing through the first conductor 231.
  • the direction of the vertical component of the external magnetic field is changed between the direction from the first core part 233 toward the second core part 234 and the opposite direction by changing the direction of the current flowing through the first conductor 231. Can be switched.
  • the third and fourth electromagnets apply a magnetic field in a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 to the magnetization free layer 23.
  • this magnetic field is referred to as a horizontal component of the external magnetic field.
  • the magnitude of the horizontal component of the external magnetic field can be changed by adjusting the magnitude of the current flowing through the second conductor 232.
  • the direction of the horizontal component of the external magnetic field is changed between the direction from the third core part 235 toward the fourth core part 236 and the opposite direction by changing the direction of the current flowing through the second conductor 232. Can be switched.
  • the external magnetic field applied to the magnetization free layer 23 is a combination of the vertical component of the external magnetic field and the horizontal component of the external magnetic field. Therefore, in the present embodiment, both the magnitude of the external magnetic field and the second direction D2 are changed by changing the magnitude and direction of the vertical component of the external magnetic field and the magnitude and direction of the horizontal component of the external magnetic field. Can do.
  • FIGS. 12 to 14 first to third examples of the configuration of the magnetoresistive effect element 2 in the present embodiment, and the first and second directions D ⁇ b> 1 and D ⁇ b> 2 in the present embodiment.
  • the first and second examples will be described.
  • 12 to 14 also show the X, Y, and Z directions shown in FIG. 2 in the first embodiment.
  • the Y direction is a direction from the front to the back in FIGS. 12 to 14.
  • FIG. 12 shows a first example of the configuration of the magnetoresistive effect element 2 and a first example of the first and second directions D1 and D2.
  • the magnetization fixed layer 21 is composed of only the first magnetic layer having the magnetization in the first direction D1, as in the first embodiment.
  • the first direction D1 is a direction parallel to the interface between the magnetization fixed layer 21 and the spacer layer 22 and is opposite to the X direction.
  • the second direction D ⁇ b> 2 is a direction that intersects the interface between the magnetization free layer 23 and the spacer layer 22.
  • the range of the angle ⁇ formed by the second direction D2 with respect to the first direction D1 is the same as that in the first embodiment.
  • FIG. 13 shows a second example of the configuration of the magnetoresistive effect element 2.
  • the magnetoresistive element 2 includes an antiferromagnetic layer 24 in addition to the magnetization fixed layer 21, the magnetization free layer 23, and the spacer layer 22.
  • the antiferromagnetic layer 24 is provided so as to be in contact with the surface of the magnetization fixed layer 21 opposite to the surface in contact with the spacer layer 22.
  • the magnetization fixed layer 21 is composed of a plurality of layers including the first magnetic layer.
  • the magnetization fixed layer 21 includes a first magnetic layer 211, a second magnetic layer 212, and a nonmagnetic layer 213 disposed between the first magnetic layer 211 and the second magnetic layer 212. And has a so-called synthetic structure.
  • the first magnetic layer 211 is in contact with the spacer layer 22.
  • the second magnetic layer 212 is in contact with the antiferromagnetic layer 24.
  • the magnetization direction of the second magnetic layer 212 is substantially fixed by exchange coupling with the antiferromagnetic layer 24.
  • the first magnetic layer 211 and the second magnetic layer 212 are antiferromagnetically coupled and the magnetization directions are opposite to each other.
  • the first magnetic layer 211 has magnetization in the first direction D1.
  • the first direction D1 shown in FIG. 13 is the same direction as the first direction D1 shown in FIG. 12, and is the direction opposite to the X direction.
  • the second magnetic layer 212 has magnetization in a direction opposite to the first direction D1.
  • an arrow drawn in the second magnetic layer 212 represents the direction of magnetization of the second magnetic layer 212.
  • the magnetization direction of the second magnetic layer 212 shown in FIG. 13 coincides with the X direction.
  • the first and second magnetic layers 211 and 212 are made of a ferromagnetic material.
  • the first and second magnetic layers 211 and 212 may be made of the same material as the ferromagnetic material constituting the magnetization fixed layer 21 in the first embodiment.
  • the nonmagnetic layer 213 is entirely made of, for example, a nonmagnetic conductive material such as Ru.
  • FIG. 14 shows a third example of the configuration of the magnetoresistive effect element 2 and a second example of the first and second directions D1 and D2.
  • the configuration of the magnetoresistive effect element 2 is basically the same as the example shown in FIG.
  • the magnetization directions of the first and second magnetic layers 211 and 212 of the magnetization fixed layer 21 are different from those shown in FIG. 13.
  • the magnetization direction of the first magnetic layer 211 that is, the first direction D1
  • the magnetization direction of the second magnetic layer 212 is opposite to the first direction D1 and coincides with the Z direction.
  • an arrow drawn in the second magnetic layer 212 represents the direction of magnetization of the second magnetic layer 212.
  • the second direction D2 is a direction intersecting the interface between the magnetization free layer 23 and the spacer layer 22.
  • the range of the angle ⁇ formed by the second direction D2 with respect to the first direction D1 is the same as that in the first embodiment.
  • At least the XZ plane perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 corresponds to the reference plane defined in the first embodiment.
  • both the magnitude of the external magnetic field and the second direction D2 can be changed as described above.
  • the central axis of magnetization vibration of the magnetization free layer 23 when ferromagnetic resonance is caused in the magnetization free layer 23 is perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22. It is possible to set the direction or a direction close thereto. By setting in this way, it is possible to prevent the anisotropic magnetic field acting on the magnetization of the magnetization free layer 23 from greatly differing depending on the magnetization direction of the magnetization free layer 23. Thereby, distortion of the waveform of the high frequency output signal can be suppressed.
  • the configuration of the resonator 1 according to the present embodiment will be described with reference to FIG.
  • the configuration of the resonator 1 according to the present embodiment is different from that of the third embodiment in the following points.
  • the resonator 1 according to the present embodiment includes an energy applying unit 104 instead of the energy applying unit 4 in the third embodiment.
  • the energy applying unit 104 applies a high frequency magnetic field to the magnetoresistive effect element 2 as energy for vibrating the magnetization of the magnetization free layer 23.
  • the energy applying unit 104 includes one or more electromagnets for generating a high frequency magnetic field.
  • the first electromagnet configured by the first core portion 233 and the first winding portion of the first conductor 231, the second core portion 234 and the second conductor 231 of the first conductor 231.
  • the second electromagnet constituted by the winding portions also serves as one or more electromagnets for generating a high-frequency magnetic field.
  • both ends of the first conducting wire 231 are referred to as input ends 231a and 231b.
  • a DC current and a high-frequency current superimposed thereon are input to the input terminals 231a and 231b.
  • a direct current on which the high-frequency current is superimposed flows through the first conducting wire 231.
  • the first and second electromagnets generate a vertical component of an external magnetic field caused by a direct current and a high frequency magnetic field caused by a high frequency current.
  • the magnetization free layer 23 of the magnetoresistive effect element 2 has a vertical component and a high frequency magnetic field generated by the first and second electromagnets and a horizontal component of the external magnetic field generated by the third and fourth electromagnets. And a combined magnetic field is applied.
  • this magnetic field is referred to as a high frequency superimposed magnetic field.
  • the direction of the external magnetic field is the second direction D2.
  • the high-frequency magnetic field changes the direction of the high-frequency superimposed magnetic field so as to vibrate about the second direction D2.
  • the frequency of change in the direction of the high-frequency superimposed magnetic field is equal to the frequency of the high-frequency current.
  • the magnetization of the magnetization free layer 23 vibrates at the frequency of the high-frequency current so that the angle formed by the magnetization direction D3 of the magnetization free layer 23 with respect to the magnetization direction D1 of the magnetization fixed layer 21 changes.
  • the resonator 1 according to the present embodiment includes a signal line 106 instead of the first signal line 6 in the third embodiment.
  • One end of the signal line 106 is electrically connected to the DC input terminal 15.
  • the other end of the signal line 106 is electrically connected to the first electrode 11.
  • the input port 5 in the third embodiment is not provided.
  • the magnetoresistive effect element 2 is supplied with a direct current on which no high-frequency current is superimposed.
  • the precession torque (the first term in the expression (1)) described with reference to the expression (1) in the first embodiment also changes.
  • the influence of the change in precession torque on the vibration of magnetization of the magnetization free layer 23 is very small compared to the damping torque.
  • the frequency of the high frequency current is equal to the ferromagnetic resonance frequency of the magnetization free layer 23
  • ferromagnetic resonance occurs in the magnetization free layer 23
  • the amplitude of magnetization vibration of the magnetization free layer 23 is maximized.
  • the amplitude of the high frequency output signal is also maximized.
  • the angle ⁇ formed by the second direction D2 with respect to the first direction D1 is preferably larger than 90 °, more than 90 °. Is more preferably 150 ° or less, and more preferably in the range of 105 ° to 135 °.
  • the third and fourth electromagnets may also serve as one or more electromagnets for generating a high-frequency magnetic field.
  • a direct current superimposed with a high-frequency current is passed through the second conducting wire 232.
  • the third and fourth electromagnets generate a horizontal component of the external magnetic field due to the direct current and a high-frequency magnetic field due to the high-frequency current.
  • the configuration of the resonator 1 according to the present embodiment will be described with reference to FIG.
  • the configuration of the resonator 1 according to the present embodiment is different from that of the third embodiment in the following points.
  • the resonator 1 according to the present embodiment includes an energy applying unit 204 instead of the energy applying unit 4 in the third embodiment.
  • the energy applying unit 204 applies a high-frequency magnetic field to the magnetoresistive effect element 2 as energy for vibrating the magnetization of the magnetization free layer 23.
  • the energy applying unit 204 includes an input port 5 and a high-frequency signal line 206 that transmits a high-frequency current based on a high-frequency input signal applied to the input port 5.
  • the configuration of the input port 5 is the same as that of the third embodiment.
  • One end of the high-frequency signal transmission line 206 is electrically connected to the terminal 51 of the input port 5.
  • the other end of the high-frequency signal transmission line 206 is electrically connected to the ground electrode 13.
  • FIG. 17 is a perspective view showing the magnetoresistive effect element 2 and its periphery.
  • the high frequency signal line 206 includes a high frequency magnetic field generator 206 a disposed in the vicinity of the magnetoresistive element 2.
  • the high-frequency magnetic field generation unit 206 a has a shape elongated in a direction parallel to the X direction, and is disposed ahead of the magnetoresistive effect element 2 and the first electrode 11 in the Z direction.
  • the boundary between the high-frequency magnetic field generation unit 206a and the other part is indicated by a dotted line.
  • the high frequency magnetic field generation unit 206a generates a high frequency magnetic field based on a high frequency current passing through the high frequency signal line 206. A part of the high frequency magnetic field is applied to the magnetoresistive effect element 2. The direction of the high-frequency magnetic field applied to the magnetoresistive effect element 2 is a direction parallel to the Y direction.
  • the external magnetic field application unit 203 includes first to fourth electromagnets, and is external to the magnetization free layer 23 of the magnetoresistive element 2 in the second direction D2. Apply a magnetic field.
  • the magnetization free layer 23 of the magnetoresistive element 2 has a vertical component of the external magnetic field generated by the first and second electromagnets, a horizontal component of the external magnetic field generated by the third and fourth electromagnets, and a high frequency.
  • a magnetic field obtained by synthesizing the high-frequency magnetic field generated by the magnetic field generation unit 206a is applied.
  • this magnetic field is referred to as a high frequency superimposed magnetic field.
  • the direction of the external magnetic field is the second direction D2.
  • the high-frequency magnetic field changes the direction of the high-frequency superimposed magnetic field so as to vibrate in a direction parallel to the Y direction with the second direction D2 as the center.
  • the frequency of change in the direction of the high-frequency superimposed magnetic field is equal to the frequency of the high-frequency current.
  • the magnetization of the magnetization free layer 23 vibrates at the frequency of the high-frequency current so that the angle formed by the magnetization direction D3 of the magnetization free layer 23 with respect to the magnetization direction D1 of the magnetization fixed layer 21 changes.
  • the resonator 1 further includes a signal line 17 and a DC input terminal 18.
  • One end of the signal line 17 is electrically connected to the first electrode 11.
  • the other end of the signal line 17 is electrically connected to the ground electrode 13.
  • the DC input terminal 18 is provided between the choke coil 14 and the ground electrode 13. In the present embodiment, the DC input terminal 15 in the third embodiment is not provided.
  • the DC current source 16 when the resonator 1 is operated, the DC current source 16 is provided between the DC input terminal 18 and the ground electrode 13 as shown in FIG. As a result, a closed circuit including the signal line 17, the magnetoresistive effect element 2, the second signal line 7, the choke coil 14, the DC input terminal 18, the DC current source 16, and the ground electrode 13 is formed.
  • the direct current source 16 generates a direct current flowing through this closed circuit.
  • a direct current flows in a direction from the magnetization free layer 23 toward the magnetization fixed layer 21. Particularly in the present embodiment, a direct current on which a high-frequency current is not superimposed is passed through the magnetoresistive effect element 2.
  • a high frequency output signal is generated due to the vibration of magnetization of the magnetization free layer 23 caused by the high frequency magnetic field applied to the magnetoresistive effect element 2.
  • Other configurations, operations, and effects in the present embodiment are the same as those in the third or fourth embodiment.
  • the resonator 1 according to the present embodiment includes a DC input terminal 18 and a signal line 19.
  • the DC input terminal 18 is provided between the choke coil 14 and the ground electrode 13.
  • One end of the signal line 19 is electrically connected to the first electrode 11.
  • the other end of the signal line 19 is electrically connected to the ground electrode 13.
  • the DC input terminal 15 in the third embodiment is not provided.
  • FIG. 19 is a perspective view showing the magnetoresistive effect element 2 and its periphery.
  • the first electrode 11 has an elongated shape in a direction parallel to the X direction.
  • the first electrode 11 has a first end located at the tip of the X direction and a second end opposite to the first end.
  • the signal line 19 is connected to the first end, and the first signal line 6 is connected to the second end.
  • the boundary between the first electrode 11 and the first signal line 6 and the boundary between the first electrode 11 and the signal line 19 are indicated by dotted lines.
  • the first signal line 6 may be connected to the first end, and the signal line 19 may be connected to the second end.
  • a direct current source 16 is provided between the direct current input terminal 18 and the ground electrode 13 as shown in FIG.
  • a closed circuit including the signal line 19, the magnetoresistive effect element 2, the second signal line 7, the choke coil 14, the DC input terminal 18, the DC current source 16, and the ground electrode 13 is formed.
  • the direct current source 16 generates a direct current flowing through this closed circuit.
  • a direct current flows in a direction from the magnetization free layer 23 toward the magnetization fixed layer 21.
  • the energy applying unit 4 in the present embodiment applies a high-frequency magnetic field and a high-frequency current to the magnetoresistive effect element 2 as energy for vibrating the magnetization of the magnetization free layer 23.
  • a high frequency current based on a high frequency input signal applied to the input port 5 passes through the first signal line 6, the first electrode 11, and the signal line 19.
  • the first electrode 11 generates a high frequency magnetic field based on the high frequency current passing through the first electrode 11.
  • a part of the high frequency magnetic field is applied to the magnetoresistive effect element 2.
  • the direction of the high-frequency magnetic field applied to the magnetoresistive effect element 2 is a direction parallel to the Y direction shown in FIG.
  • a part of the high-frequency current supplied to the first electrode 11 is superimposed on the direct current flowing through the magnetoresistive effect element 2 and applied to the magnetoresistive effect element 2.
  • An output signal is generated.
  • Other configurations, operations, and effects in the present embodiment are the same as those in the third or fifth embodiment.
  • the external magnetic field application unit in the present invention may include one or more conductors arranged near the magnetization free layer 23 instead of one or more electromagnets.
  • the one or more conductors generate a magnetic field around them when energized. A part of this magnetic field becomes an external magnetic field.
  • the external magnetic field application unit in the present invention may include one or more permanent magnets instead of one or more electromagnets.
  • one or more permanent magnets that generate a vertical component of the external magnetic field may be provided instead of the first and second electromagnets.
  • the second direction D2 which is the direction of the external magnetic field can be changed by using the third and fourth electromagnets to change at least one of the magnitude and direction of the horizontal component of the external magnetic field.
  • one or more permanent magnets that generate a horizontal component of the external magnetic field may be provided instead of the third and fourth electromagnets.
  • the second direction D2, which is the direction of the external magnetic field can be changed by changing at least one of the magnitude and direction of the vertical component of the external magnetic field using the first and second electromagnets. It is.

Abstract

A resonator 1 is provided with a magnetoresistive effect element 2, an external magnetic field application unit 3, and an energy-imparting unit 4. The magnetoresistive effect element 2 includes: a magnetization fixed layer 21 having magnetization in a first direction; a magnetization free layer 23 having magnetization for which the direction changes; and a spacer layer 22 placed between the magnetization fixed layer 21 and the magnetization free layer 23. The external magnetic field application unit 3 applies an external magnetic field of a second direction to the magnetization free layer 23. The energy-imparting unit 4 imparts to the magnetoresistive effect element 2 energy for vibrating the magnetization of the magnetization free layer 23. The angle formed by the second direction with respect to the first direction is in the range of 90-150°.

Description

共振器Resonator
　本発明は、磁気抵抗効果素子を用いた共振器に関する。 The present invention relates to a resonator using a magnetoresistive effect element.
　近年、携帯電話機等の移動体通信機器の高機能化に伴い、無線通信の高速化が進められている。通信速度は使用する周波数帯域の帯域幅に比例するため、通信に必要な周波数帯域の数は増加し、それに伴い、移動体通信機器に搭載されるバンドパスフィルタ等の高周波フィルタの数も増加している。共振器は、バンドパスフィルタ等に広く利用されている。 In recent years, with the enhancement of functions of mobile communication devices such as mobile phones, the speed of wireless communication has been increased. Since the communication speed is proportional to the bandwidth of the frequency band to be used, the number of frequency bands necessary for communication increases, and accordingly, the number of high-frequency filters such as bandpass filters mounted on mobile communication devices also increases. ing. A resonator is widely used for a band-pass filter or the like.
　一方、近年、高周波フィルタ等の高周波デバイスへ応用できる可能性のある技術として、スピントロニクスが注目されている。スピントロニクスの中で特に注目されている技術の１つに、強磁性共鳴を利用した技術がある。磁界中に置かれた強磁性体の磁化は、磁化の方向が変化するような振動を行い得る。この磁化の振動は、例えば歳差運動である。強磁性共鳴は、特定の周波数で変動するエネルギの付与によって、その特定の周波数で磁化が振動し、且つ磁化の振動の振幅が最大になる現象である。以下、磁化の振動の振幅が最大になるときの磁化の振動の周波数を強磁性共鳴周波数と言う。強磁性共鳴を発生させるエネルギとしては、高周波磁界や高周波電流等がある。 On the other hand, in recent years, spintronics has attracted attention as a technology that can be applied to high-frequency devices such as high-frequency filters. One technique that has attracted particular attention in spintronics is a technique using ferromagnetic resonance. The magnetization of a ferromagnetic material placed in a magnetic field can oscillate such that the direction of magnetization changes. This magnetization vibration is, for example, precession. Ferromagnetic resonance is a phenomenon in which magnetization is oscillated at a specific frequency and the amplitude of vibration of the magnetization is maximized by applying energy varying at a specific frequency. Hereinafter, the frequency of magnetization vibration when the amplitude of magnetization vibration becomes maximum is referred to as a ferromagnetic resonance frequency. Examples of energy that generates ferromagnetic resonance include a high-frequency magnetic field and a high-frequency current.
　以下、スピントロニクスを利用する素子をスピントロニクス素子と言う。代表的なスピントロニクス素子としては、磁化固定層と、磁化の方向が変化する磁化自由層と、磁化固定層と磁化自由層の間に配置されたスペーサ層とを含む磁気抵抗効果素子が知られている。 Hereinafter, an element using spintronics is referred to as a spintronic element. As a typical spintronic element, there is known a magnetoresistive element including a magnetization fixed layer, a magnetization free layer whose magnetization direction changes, and a spacer layer disposed between the magnetization fixed layer and the magnetization free layer. Yes.
　特許文献１には、磁気抵抗効果素子からなる周波数変換素子と、周波数変換素子に磁界を印加するための機構と、周波数変換素子に局部発振信号を印加するための局部発振器と、周波数変換素子と電気的に接続され、且つ外部入力信号を入力するための入力端子とを備えた周波数変換装置が記載されている。 Patent Document 1 discloses a frequency conversion element including a magnetoresistive effect element, a mechanism for applying a magnetic field to the frequency conversion element, a local oscillator for applying a local oscillation signal to the frequency conversion element, a frequency conversion element, A frequency conversion device that is electrically connected and has an input terminal for inputting an external input signal is described.
国際公開第２０１０／１１９５６９号International Publication No. 2010/119568
　磁気抵抗効果素子の磁化自由層は強磁性共鳴を生じ得ることから、磁気抵抗効果素子を用いた共振器を実現できる可能性がある。磁気抵抗効果素子を用いた共振器を実現する場合、磁化自由層の磁化の方向が変化するような磁化自由層の磁化の振動に伴って磁気抵抗効果素子の抵抗値が変化する現象を利用することが考えられる。 Since the magnetization free layer of the magnetoresistive effect element can cause ferromagnetic resonance, there is a possibility that a resonator using the magnetoresistive effect element can be realized. When realizing a resonator using a magnetoresistive effect element, use a phenomenon in which the resistance value of the magnetoresistive effect element changes in accordance with the magnetization oscillation of the magnetization free layer such that the magnetization direction of the magnetization free layer changes. It is possible.
　磁気抵抗効果素子を用いた実用的な共振器を実現するためには、強磁性共鳴を生じさせたときの磁気抵抗効果素子の抵抗値の変化量が十分に大きくなるような工夫が必要である。しかし、従来は、そのような工夫について、十分に検討されていなかった。 In order to realize a practical resonator using a magnetoresistive effect element, it is necessary to devise such that the amount of change in the resistance value of the magnetoresistive effect element is sufficiently large when ferromagnetic resonance occurs. . However, conventionally, such a device has not been sufficiently studied.
　本発明はかかる問題点に鑑みてなされたもので、その目的は、磁気抵抗効果素子を用いた実用的な共振器を提供することにある。 The present invention has been made in view of such problems, and an object thereof is to provide a practical resonator using a magnetoresistive effect element.
　本発明の共振器は、磁気抵抗効果素子と、外部磁界印加部と、エネルギ付与部とを備えている。磁気抵抗効果素子は、少なくとも第１の磁性層からなる磁化固定層と、方向が変化する磁化を有する磁化自由層と、磁化固定層と磁化自由層の間に配置され且つ第１の磁性層に接するスペーサ層とを含んでいる。第１の磁性層は、第１の方向の磁化を有している。外部磁界印加部は、磁気抵抗効果素子の磁化自由層に対して、第２の方向の静磁界である外部磁界を印加する。エネルギ付与部は、磁化自由層の磁化を振動させるためのエネルギを磁気抵抗効果素子に付与する。第２の方向が第１の方向に対してなす角度は、９０°～１５０°の範囲内である。 The resonator of the present invention includes a magnetoresistive effect element, an external magnetic field application unit, and an energy application unit. The magnetoresistive effect element includes at least a magnetization fixed layer made of a first magnetic layer, a magnetization free layer having magnetization whose direction changes, and is disposed between the magnetization fixed layer and the magnetization free layer and is attached to the first magnetic layer. And a spacer layer in contact therewith. The first magnetic layer has magnetization in the first direction. The external magnetic field application unit applies an external magnetic field, which is a static magnetic field in the second direction, to the magnetization free layer of the magnetoresistive effect element. The energy applying unit applies energy for vibrating the magnetization of the magnetization free layer to the magnetoresistive effect element. The angle formed by the second direction with respect to the first direction is in the range of 90 ° to 150 °.
　本発明の共振器において、エネルギ付与部は、高周波電流を、前記エネルギとして磁気抵抗効果素子に付与してもよい。あるいは、エネルギ付与部は、高周波磁界を、前記エネルギとして磁気抵抗効果素子に付与してもよい。 In the resonator of the present invention, the energy applying unit may apply a high frequency current to the magnetoresistive effect element as the energy. Or an energy provision part may provide a high frequency magnetic field to a magnetoresistive effect element as the said energy.
　また、本発明の共振器において、第２の方向が第１の方向に対してなす角度は、１０５°～１３５°の範囲内であってもよい。 In the resonator of the present invention, the angle formed by the second direction with respect to the first direction may be in the range of 105 ° to 135 °.
　また、本発明の共振器において、第１の方向と第２の方向の少なくとも一方は、磁化自由層とスペーサ層の界面と交差する方向であってもよい。 In the resonator of the present invention, at least one of the first direction and the second direction may be a direction intersecting with the interface between the magnetization free layer and the spacer layer.
　また、本発明の共振器において、第２の方向は、磁化自由層とスペーサ層の界面に垂直な方向であってもよい。あるいは、第２の方向は、磁化自由層とスペーサ層の界面に平行な方向であってもよい。 In the resonator of the present invention, the second direction may be a direction perpendicular to the interface between the magnetization free layer and the spacer layer. Alternatively, the second direction may be a direction parallel to the interface between the magnetization free layer and the spacer layer.
　また、本発明の共振器において、第１の方向は、磁化固定層とスペーサ層の界面に垂直な方向であってもよい。あるいは、第１の方向は、磁化固定層とスペーサ層の界面に平行な方向であってもよい。 In the resonator of the present invention, the first direction may be a direction perpendicular to the interface between the magnetization fixed layer and the spacer layer. Alternatively, the first direction may be a direction parallel to the interface between the magnetization fixed layer and the spacer layer.
　また、本発明の共振器において、外部磁界印加部は、外部磁界の大きさを変化可能であってもよい。また、外部磁界印加部は、第２の方向を変化可能であってもよい。 In the resonator of the present invention, the external magnetic field application unit may be capable of changing the magnitude of the external magnetic field. Further, the external magnetic field application unit may be capable of changing the second direction.
　また、本発明の共振器は、更に、磁化自由層の磁化の振動に起因する高周波出力信号が現れる出力ポートを備えていてもよい。 In addition, the resonator of the present invention may further include an output port where a high frequency output signal resulting from the vibration of magnetization of the magnetization free layer appears.
　本発明の共振器では、磁気抵抗効果素子の磁化自由層の強磁性共鳴周波数と等しい周波数で変動するエネルギを磁気抵抗効果素子に付与することによって、磁化自由層に強磁性共鳴を生じさせることができる。また、本発明では、第２の方向が第１の方向に対してなす角度を、９０°～１５０°の範囲内の角度としている。これにより、磁化自由層に強磁性共鳴を生じさせたときの磁気抵抗効果素子の抵抗値の変化量が十分に大きくなる。その結果、本発明によれば、磁気抵抗効果素子を用いた実用的な共振器を実現することが可能になるという効果を奏する。 In the resonator of the present invention, ferromagnetic resonance can be caused in the magnetization free layer by applying energy varying at a frequency equal to the ferromagnetic resonance frequency of the magnetization free layer of the magnetoresistive effect element to the magnetoresistive effect element. it can. In the present invention, the angle formed by the second direction with respect to the first direction is an angle within the range of 90 ° to 150 °. As a result, the amount of change in the resistance value of the magnetoresistive element when ferromagnetic resonance is generated in the magnetization free layer becomes sufficiently large. As a result, according to the present invention, it is possible to realize a practical resonator using a magnetoresistive effect element.
本発明の第１の実施の形態に係る共振器を模式的に示す説明図である。It is explanatory drawing which shows typically the resonator which concerns on the 1st Embodiment of this invention. 本発明の第１の実施の形態における第１ないし第３の方向を示す説明図である。It is explanatory drawing which shows the 1st thru | or 3rd direction in the 1st Embodiment of this invention. 図２における第２の方向が第１の方向に対してなす角度を示す説明図である。It is explanatory drawing which shows the angle which the 2nd direction in FIG. 2 makes with respect to a 1st direction. 本発明の第１の実施の形態における磁気抵抗効果素子の抵抗変化率の特性を示す特性図である。It is a characteristic view which shows the characteristic of the resistance change rate of the magnetoresistive effect element in the 1st Embodiment of this invention. 本発明の第１の実施の形態に係る共振器の通過特性の一例を示す特性図である。It is a characteristic view which shows an example of the passage characteristic of the resonator which concerns on the 1st Embodiment of this invention. 磁化自由層の磁化の挙動を模式的に示す説明図である。It is explanatory drawing which shows typically the behavior of the magnetization of a magnetization free layer. スピントランスファートルクの大きさを決めるパラメータの特性を示す特性図である。It is a characteristic view showing the characteristic of the parameter that determines the magnitude of the spin transfer torque. 本発明の第２の実施の形態に係る共振器を模式的に示す説明図である。It is explanatory drawing which shows typically the resonator which concerns on the 2nd Embodiment of this invention. 本発明の第２の実施の形態における第１ないし第３の方向の第１の例を示す説明図である。It is explanatory drawing which shows the 1st example of the 1st thru | or 3rd direction in the 2nd Embodiment of this invention. 本発明の第２の実施の形態における第１ないし第３の方向の第２の例を示す説明図である。It is explanatory drawing which shows the 2nd example of the 1st thru | or 3rd direction in the 2nd Embodiment of this invention. 本発明の第３の実施の形態に係る共振器を模式的に示す説明図である。It is explanatory drawing which shows typically the resonator which concerns on the 3rd Embodiment of this invention. 本発明の第３の実施の形態における磁気抵抗効果素子の構成の第１の例と第１ないし第３の方向の第１の例を示す説明図である。It is explanatory drawing which shows the 1st example of a structure of the magnetoresistive effect element in the 3rd Embodiment of this invention, and the 1st example of the 1st thru | or 3rd direction. 本発明の第３の実施の形態における磁気抵抗効果素子の構成の第２の例を示す説明図である。It is explanatory drawing which shows the 2nd example of a structure of the magnetoresistive effect element in the 3rd Embodiment of this invention. 本発明の第３の実施の形態における磁気抵抗効果素子の構成の第３の例と第１ないし第３の方向の第２の例を示す説明図である。It is explanatory drawing which shows the 3rd example of a structure of the magnetoresistive effect element in the 3rd Embodiment of this invention, and the 2nd example of the 1st thru | or 3rd direction. 本発明の第４の実施の形態に係る共振器を模式的に示す説明図である。It is explanatory drawing which shows typically the resonator which concerns on the 4th Embodiment of this invention. 本発明の第５の実施の形態に係る共振器を模式的に示す説明図である。It is explanatory drawing which shows typically the resonator which concerns on the 5th Embodiment of this invention. 本発明の第５の実施の形態における磁気抵抗効果素子とその周辺を示す斜視図である。It is a perspective view which shows the magnetoresistive effect element in the 5th Embodiment of this invention, and its periphery. 本発明の第６の実施の形態に係る共振器を模式的に示す説明図である。It is explanatory drawing which shows typically the resonator which concerns on the 6th Embodiment of this invention. 本発明の第６の実施の形態における磁気抵抗効果素子とその周辺を示す斜視図である。It is a perspective view which shows the magnetoresistive effect element in the 6th Embodiment of this invention, and its periphery.
［第１の実施の形態］
　以下、本発明の実施の形態について図面を参照して詳細に説明する。始めに、図１を参照して、本発明の第１の実施の形態に係る共振器の構成について説明する。本実施の形態に係る共振器１は、磁気抵抗効果素子２と、外部磁界印加部３と、エネルギ付与部４とを備えている。磁気抵抗効果素子２は、少なくとも第１の磁性層からなる磁化固定層２１と、方向が変化する磁化を有する磁化自由層２３と、磁化固定層２１と磁化自由層２３の間に配置され且つ第１の磁性層に接するスペーサ層２２とを含んでいる。第１の磁性層は、第１の方向の磁化を有している。 [First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the configuration of the resonator according to the first embodiment of the invention will be described with reference to FIG. The resonator 1 according to the present embodiment includes a magnetoresistive effect element 2, an external magnetic field application unit 3, and an energy application unit 4. The magnetoresistive effect element 2 is disposed between the magnetization fixed layer 21 having at least a first magnetic layer, a magnetization free layer 23 having magnetization whose direction changes, and between the magnetization fixed layer 21 and the magnetization free layer 23 and And a spacer layer 22 in contact with one magnetic layer. The first magnetic layer has magnetization in the first direction.
　第１の磁性層は、磁化自由層２３に比べて、磁化の方向が変化しにくく、保磁力が大きい性質を有している。そのため、第１の磁性層の磁化の方向である第１の方向は、磁化自由層２３の磁化の方向に比べて変化しにくい。第１の方向は、実質的にあるいは完全に固定されていてもよい。 The first magnetic layer has a property that the magnetization direction is less likely to change and the coercive force is larger than that of the magnetization free layer 23. Therefore, the first direction, which is the magnetization direction of the first magnetic layer, is less likely to change than the magnetization direction of the magnetization free layer 23. The first direction may be substantially or completely fixed.
　磁化固定層２１は、第１の磁性層のみからなるものであってもよいし、第１の磁性層に加えて他の層を含むものであってもよい。本実施の形態では、磁化固定層２１が第１の磁性層のみからなる場合について説明する。本実施の形態では、第１の磁性層の磁化の方向である第１の方向は、磁化固定層２１の磁化の方向でもある。磁化固定層２１が第１の磁性層を含む複数の層からなる例については、後で説明する第３の実施の形態で示す。 The magnetization fixed layer 21 may be composed of only the first magnetic layer, or may include other layers in addition to the first magnetic layer. In the present embodiment, the case where the magnetization fixed layer 21 includes only the first magnetic layer will be described. In the present embodiment, the first direction, which is the magnetization direction of the first magnetic layer, is also the magnetization direction of the magnetization fixed layer 21. An example in which the magnetization fixed layer 21 includes a plurality of layers including the first magnetic layer will be described in a third embodiment described later.
　また、磁気抵抗効果素子２は、磁気抵抗効果素子２を構成する複数の層の積層方向の両端に位置する第１の端面２ａと第２の端面２ｂを有している。磁化固定層２１、スペーサ層２２および磁化自由層２３は、第２の端面２ｂ側からこの順に積層されている。 Further, the magnetoresistive effect element 2 has a first end face 2a and a second end face 2b located at both ends in the stacking direction of a plurality of layers constituting the magnetoresistive effect element 2. The magnetization fixed layer 21, the spacer layer 22, and the magnetization free layer 23 are laminated in this order from the second end face 2b side.
　外部磁界印加部３は、磁化自由層２３に対して、第２の方向の静磁界である外部磁界を印加する。外部磁界印加部３の構成と、第１および第２の方向については、後で詳しく説明する。 The external magnetic field application unit 3 applies an external magnetic field that is a static magnetic field in the second direction to the magnetization free layer 23. The configuration of the external magnetic field application unit 3 and the first and second directions will be described in detail later.
　磁化自由層２３の磁化に作用する有効磁界は、磁化自由層２３の磁化に作用する全ての種類の磁界が合成されたものである。磁化自由層２３の磁化に作用する磁界には、上記の外部磁界の他に、磁気異方性磁界、交換磁界、反磁界等がある。本実施の形態では、磁化自由層２３の磁化に作用する有効磁界の方向は、外部磁界の方向である第２の方向と一致するか、ほぼ一致する。 The effective magnetic field acting on the magnetization of the magnetization free layer 23 is a combination of all kinds of magnetic fields acting on the magnetization of the magnetization free layer 23. In addition to the above external magnetic field, the magnetic field acting on the magnetization of the magnetization free layer 23 includes a magnetic anisotropic magnetic field, an exchange magnetic field, a demagnetizing field, and the like. In the present embodiment, the direction of the effective magnetic field acting on the magnetization of the magnetization free layer 23 matches or substantially matches the second direction that is the direction of the external magnetic field.
　エネルギ付与部４は、磁化自由層２３の磁化を振動させるためのエネルギを、磁気抵抗効果素子２に付与するものである。本実施の形態では、上記エネルギとして、高周波電流を用いる。エネルギ付与部４は、高周波電流を、エネルギとして磁気抵抗効果素子２に付与することができるように構成されている。具体的に説明すると、エネルギ付与部４は、高周波入力信号が印加される入力ポート５と、入力ポート５に印加された高周波入力信号に基づく高周波電流を磁気抵抗効果素子２に伝送する第１の信号線路６とを含んでいる。高周波入力信号は、例えば、１００ＭＨｚ以上の周波数を有する信号である。高周波電流の周波数は、高周波入力信号の周波数と等しい。 The energy applying unit 4 applies energy for vibrating the magnetization of the magnetization free layer 23 to the magnetoresistive effect element 2. In the present embodiment, a high frequency current is used as the energy. The energy applying unit 4 is configured to apply a high frequency current to the magnetoresistive effect element 2 as energy. More specifically, the energy applying unit 4 includes a first input port 5 to which a high frequency input signal is applied and a high frequency current based on the high frequency input signal applied to the input port 5 to the magnetoresistive element 2. Signal line 6. A high frequency input signal is a signal which has a frequency of 100 MHz or more, for example. The frequency of the high frequency current is equal to the frequency of the high frequency input signal.
　共振器１は、更に、出力ポート８と、第２の信号線路７とを備えている。磁気抵抗効果素子２は、磁化自由層２３の磁化の振動に起因する高周波出力信号を生成する。第２の信号線路７は、この高周波出力信号を磁気抵抗効果素子２から出力ポート８に伝送する。出力ポート８には、この高周波出力信号が現れる。回路構成上、磁気抵抗効果素子２は、入力ポート５と出力ポート８との間に位置している。 The resonator 1 further includes an output port 8 and a second signal line 7. The magnetoresistive effect element 2 generates a high frequency output signal resulting from the vibration of magnetization of the magnetization free layer 23. The second signal line 7 transmits this high frequency output signal from the magnetoresistive effect element 2 to the output port 8. This high frequency output signal appears at the output port 8. In terms of circuit configuration, the magnetoresistive element 2 is located between the input port 5 and the output port 8.
　共振器１は、更に、第１の電極１１と、第２の電極１２と、グランド電極１３とを備えている。第１の電極１１と第２の電極１２は、それらの間に磁気抵抗効果素子２が介在するように設けられている。第１の電極１１と第２の電極１２は、高周波電流および後述する直流電流を、磁気抵抗効果素子２に流すために用いられる。第１の電極１１は、磁気抵抗効果素子２の第１の端面２ａに接している。第２の電極１２は、磁気抵抗効果素子２の第２の端面２ｂに接している。直流電流は、磁気抵抗効果素子２を構成する各層の面と交差する方向、例えば磁気抵抗効果素子２を構成する各層の面に対して垂直な方向に流れる。 The resonator 1 further includes a first electrode 11, a second electrode 12, and a ground electrode 13. The first electrode 11 and the second electrode 12 are provided such that the magnetoresistive element 2 is interposed therebetween. The first electrode 11 and the second electrode 12 are used for flowing a high-frequency current and a direct current described later to the magnetoresistive effect element 2. The first electrode 11 is in contact with the first end face 2 a of the magnetoresistive effect element 2. The second electrode 12 is in contact with the second end face 2 b of the magnetoresistive effect element 2. The direct current flows in a direction intersecting the surface of each layer constituting the magnetoresistive effect element 2, for example, in a direction perpendicular to the surface of each layer constituting the magnetoresistive effect element 2.
　図１に示した例では、入力ポート５は、一対の端子５１，５２を有している。第１の信号線路６の一端は、端子５１に電気的に接続されている。第１の信号線路６の他端は、第１の電極１１に電気的に接続されている。 In the example shown in FIG. 1, the input port 5 has a pair of terminals 51 and 52. One end of the first signal line 6 is electrically connected to the terminal 51. The other end of the first signal line 6 is electrically connected to the first electrode 11.
　また、図１に示した例では、出力ポート８は、一対の端子８１，８２を有している。第２の信号線路７の一端は、端子８１に電気的に接続されている。第２の信号線路７の他端は、第２の電極１２に電気的に接続されている。 Further, in the example shown in FIG. 1, the output port 8 has a pair of terminals 81 and 82. One end of the second signal line 7 is electrically connected to the terminal 81. The other end of the second signal line 7 is electrically connected to the second electrode 12.
　入力ポート５の端子５２と出力ポート８の端子８２は、それぞれ、グランド電極１３に電気的に接続されている。グランド電極１３の電位は、基準電位として用いられる。 The terminal 52 of the input port 5 and the terminal 82 of the output port 8 are each electrically connected to the ground electrode 13. The potential of the ground electrode 13 is used as a reference potential.
　第１および第２の電極１１，１２は、例えば、Ａｌ、Ｔａ、Ｃｕ、Ａｕ、ＡｕＣｕおよびＲｕのうちのいずれかよりなる単層の膜によって構成されていてもよいし、それぞれこれらの材料のうちのいずれかよりなる複数の膜の積層体によって構成されていてもよい。 The first and second electrodes 11 and 12 may be composed of a single layer film made of any one of Al, Ta, Cu, Au, AuCu, and Ru, for example. You may be comprised by the laminated body of the some film | membrane which consists of either of them.
　信号線路６，７およびグランド電極１３は、マイクロストリップラインまたはコプレーナウェーブガイドによって構成されていてもよい。 The signal lines 6 and 7 and the ground electrode 13 may be configured by a microstrip line or a coplanar waveguide.
　共振器１は、更に、チョークコイル１４と、直流入力端子１５とを備えている。チョークコイル１４の一端は、第２の信号線路７に電気的に接続されている。チョークコイル１４の他端は、グランド電極１３に電気的に接続されている。直流入力端子１５は、第１の信号線路６に電気的に接続されている。回路構成上、磁気抵抗効果素子２は、直流入力端子１５とチョークコイル１４の間に位置している。直流入力端子１５には直流電流が入力され、この直流電流が磁気抵抗効果素子２に供給される。 The resonator 1 further includes a choke coil 14 and a DC input terminal 15. One end of the choke coil 14 is electrically connected to the second signal line 7. The other end of the choke coil 14 is electrically connected to the ground electrode 13. The DC input terminal 15 is electrically connected to the first signal line 6. In terms of circuit configuration, the magnetoresistive element 2 is located between the DC input terminal 15 and the choke coil 14. A direct current is input to the direct current input terminal 15, and this direct current is supplied to the magnetoresistive element 2.
　チョークコイル１４は、インダクタンスを有している。これにより、チョークコイル１４のインピーダンスは、チョークコイル１４を通過する電流の周波数が高くなるほど大きくなる。従って、チョークコイル１４は、第２の信号線路７を通過する直流電流を通過させてグランド電極１３に流すと共に、第２の信号線路７を通過する高周波出力信号に対しては高いインピーダンスを示す。 The choke coil 14 has an inductance. Thereby, the impedance of the choke coil 14 increases as the frequency of the current passing through the choke coil 14 increases. Therefore, the choke coil 14 allows a direct current passing through the second signal line 7 to pass through the ground electrode 13 and exhibits a high impedance to a high-frequency output signal passing through the second signal line 7.
　チョークコイル１４としては、例えば、チップインダクタまたは線路が用いられる。チョークコイル１４のインダクタンスは、１０ｎＨ以上であることが好ましい。なお、共振器１は、チョークコイル１４の代わりに、インダクタンス成分を有する抵抗素子を備えていてもよい。 As the choke coil 14, for example, a chip inductor or a line is used. The inductance of the choke coil 14 is preferably 10 nH or more. The resonator 1 may include a resistance element having an inductance component instead of the choke coil 14.
　共振器１を動作させる際には、図１に示したように、直流入力端子１５とグランド電極１３の間に直流電流源１６が設けられる。これにより、直流電流源１６、直流入力端子１５、第１の信号線路６、磁気抵抗効果素子２、第２の信号線路７、チョークコイル１４およびグランド電極１３を含む閉回路が形成される。直流電流源１６は、この閉回路を流れる直流電流を発生する。磁気抵抗効果素子２では、磁化自由層２３から磁化固定層２１に向かう方向に直流電流が流れる。 When the resonator 1 is operated, a DC current source 16 is provided between the DC input terminal 15 and the ground electrode 13 as shown in FIG. As a result, a closed circuit including the DC current source 16, the DC input terminal 15, the first signal line 6, the magnetoresistive effect element 2, the second signal line 7, the choke coil 14, and the ground electrode 13 is formed. The direct current source 16 generates a direct current flowing through this closed circuit. In the magnetoresistive effect element 2, a direct current flows in a direction from the magnetization free layer 23 toward the magnetization fixed layer 21.
　直流電流源１６は、例えば、直流電圧源と抵抗とを組み合わせた回路によって構成される。抵抗としては、可変抵抗または固定抵抗が用いられる。可変抵抗を用いた場合には、直流電流の大きさを変えることができる。固定抵抗を用いた場合には、直流電流は、一定値になる。なお、第１の信号線路６を通過する高周波電流が直流電流源１６に流れることを阻止するために、直流入力端子１５と直流電流源１６との間に、チョークコイルまたはインダクタンス成分を有する抵抗素子を設けてもよい。 The DC current source 16 is configured by a circuit combining a DC voltage source and a resistor, for example. A variable resistor or a fixed resistor is used as the resistor. When a variable resistor is used, the magnitude of the direct current can be changed. When a fixed resistor is used, the direct current becomes a constant value. In order to prevent high-frequency current passing through the first signal line 6 from flowing to the DC current source 16, a resistance element having a choke coil or an inductance component between the DC input terminal 15 and the DC current source 16 is used. May be provided.
　また、直流電流源１６の代わりに、直流入力端子１５とグランド電極１３の間に、直流電圧源を設けてもよい。直流電圧源は、磁気抵抗効果素子２に印加される直流電圧を発生する。直流電圧源と磁気抵抗効果素子２は、磁化自由層２３が磁化固定層２１よりも高電位となるような直流電圧が磁気抵抗効果素子２に印加されるように接続される。これにより、磁気抵抗効果素子２では、磁化自由層２３から磁化固定層２１に向かう方向に直流電流が流れる。直流電圧源は、一定の直流電圧を発生可能なものであってもよいし、発生する直流電圧の大きさが変化可能なものであってもよい。 Further, instead of the DC current source 16, a DC voltage source may be provided between the DC input terminal 15 and the ground electrode 13. The DC voltage source generates a DC voltage applied to the magnetoresistive effect element 2. The DC voltage source and the magnetoresistive effect element 2 are connected so that a DC voltage is applied to the magnetoresistive effect element 2 so that the magnetization free layer 23 has a higher potential than the magnetization fixed layer 21. Thereby, in the magnetoresistive effect element 2, a direct current flows in a direction from the magnetization free layer 23 toward the magnetization fixed layer 21. The DC voltage source may be capable of generating a constant DC voltage, or may be capable of changing the magnitude of the generated DC voltage.
　なお、本明細書において、直流電流とは、時間によって方向が変化しない電流を言う。直流電流には、時間によって大きさが変化しない電流と、時間によって大きさが変化する電流とが含まれる。また、本明細書において、直流電圧とは、時間によって方向が変化しない電圧を言う。直流電圧には、時間によって大きさが変化しない電圧と、時間によって大きさが変化する電圧とが含まれる。 In this specification, the direct current means a current whose direction does not change with time. The direct current includes a current whose magnitude does not change with time and a current whose magnitude changes with time. In this specification, the DC voltage refers to a voltage whose direction does not change with time. The DC voltage includes a voltage whose magnitude does not change with time and a voltage whose magnitude changes with time.
　グランド電極１３は共振器１の外部のものとすることもできる。この場合、共振器１は、入力ポート５の端子５２、出力ポート８の端子８２およびチョークコイル１４の他端がグランド電極１３に電気的に接続されて用いられる。 The ground electrode 13 may be external to the resonator 1. In this case, the resonator 1 is used with the terminal 52 of the input port 5, the terminal 82 of the output port 8, and the other end of the choke coil 14 electrically connected to the ground electrode 13.
　ここで、磁気抵抗効果素子２について更に詳しく説明する。磁気抵抗効果素子２では、磁化固定層２１の磁化と磁化自由層２３の磁化が相互作用することによって磁気抵抗効果が発現する。具体的に説明すると、磁化自由層２３の磁化の方向が磁化固定層２１の磁化の方向に対してなす角度が０°から１８０°に近づくに従って、磁気抵抗効果素子２の抵抗値が大きくなる。 Here, the magnetoresistive effect element 2 will be described in more detail. In the magnetoresistive effect element 2, the magnetoresistive effect is manifested by the interaction between the magnetization of the magnetization fixed layer 21 and the magnetization of the magnetization free layer 23. Specifically, as the angle formed by the magnetization direction of the magnetization free layer 23 with respect to the magnetization direction of the magnetization fixed layer 21 approaches from 0 ° to 180 °, the resistance value of the magnetoresistive effect element 2 increases.
　磁化固定層２１は、強磁性材料によって構成されている。磁化固定層２１を構成する強磁性材料としては、例えば、Ｆｅ、Ｃｏ、Ｎｉ、ＮｉＦｅ、ＦｅＣｏ、ＦｅＣｏＢ等の高スピン分極率材料や、ホイスラー合金が用いられる。磁化固定層２１の厚みは、１～１０ｎｍの範囲内であることが好ましい。 The magnetization fixed layer 21 is made of a ferromagnetic material. As the ferromagnetic material constituting the magnetization fixed layer 21, for example, a high spin polarizability material such as Fe, Co, Ni, NiFe, FeCo, FeCoB, or a Heusler alloy is used. The thickness of the magnetization fixed layer 21 is preferably in the range of 1 to 10 nm.
　磁気抵抗効果素子２は、更に、磁化固定層２１の磁化の方向を固定するための反強磁性層を含んでいてもよい。反強磁性層は、磁化固定層２１におけるスペーサ層２２に接する面とは反対側の面に接するように設けられる。反強磁性層は、磁化固定層２１との交換結合により、磁化固定層２１の磁化の方向を固定する。反強磁性層の材料としては、例えば、ＦｅＯ、ＣｏＯ、ＮｉＯ、ＣｕＦｅＳ2、ＩｒＭｎ、ＦｅＭｎ、ＰｔＭｎ、ＣｒおよびＭｎのいずれかが用いられる。磁化固定層２１の磁化の方向は、反強磁性層を用いずに、結晶構造や形状等に基づく磁気異方性によって固定してもよい。磁気抵抗効果素子２が反強磁性層を含む例については、後で説明する第３の実施の形態で示す。 The magnetoresistive effect element 2 may further include an antiferromagnetic layer for fixing the magnetization direction of the magnetization fixed layer 21. The antiferromagnetic layer is provided so as to be in contact with a surface of the magnetization fixed layer 21 opposite to the surface in contact with the spacer layer 22. The antiferromagnetic layer fixes the magnetization direction of the magnetization fixed layer 21 by exchange coupling with the magnetization fixed layer 21. As the material of the antiferromagnetic layer, for example, any of FeO, CoO, NiO, CuFeS 2 , IrMn, FeMn, PtMn, Cr, and Mn is used. The magnetization direction of the magnetization fixed layer 21 may be fixed by magnetic anisotropy based on the crystal structure, shape, etc. without using the antiferromagnetic layer. An example in which the magnetoresistive element 2 includes an antiferromagnetic layer will be described in a third embodiment described later.
　スペーサ層２２は、その全体が非磁性材料によって構成されていてもよい。スペーサ層２２を構成する非磁性材料は、導電材料でもよいし、絶縁材料でもよいし、半導体材料でもよい。スペーサ層２２を構成する非磁性の導電材料としては、Ｃｕ、Ａｇ、Ａｕ、Ｒｕ等が挙げられる。スペーサ層２２を構成する非磁性の絶縁材料としては、Ａｌ2Ｏ3、ＭｇＯ等が挙げられる。スペーサ層２２の全体が非磁性の導電材料または絶縁材料によって構成されている場合、スペーサ層２２の厚みは、０．５～３．０ｎｍの範囲内であることが好ましい。 The entire spacer layer 22 may be made of a nonmagnetic material. The nonmagnetic material constituting the spacer layer 22 may be a conductive material, an insulating material, or a semiconductor material. Examples of the nonmagnetic conductive material constituting the spacer layer 22 include Cu, Ag, Au, and Ru. Examples of the nonmagnetic insulating material constituting the spacer layer 22 include Al 2 O 3 and MgO. When the entire spacer layer 22 is made of a nonmagnetic conductive material or insulating material, the thickness of the spacer layer 22 is preferably in the range of 0.5 to 3.0 nm.
　スペーサ層２２を構成する非磁性の半導体材料としては、例えば、Ｚｎ、Ｉｎ、Ｓｎ、Ｇａのうちの１つ以上を含む酸化物半導体が挙げられる。スペーサ層２２の全体が非磁性の半導体材料によって構成されている場合、スペーサ層２２の厚みは、１．０～４．０ｎｍの範囲内であることが好ましい。 Examples of the nonmagnetic semiconductor material constituting the spacer layer 22 include an oxide semiconductor containing one or more of Zn, In, Sn, and Ga. When the entire spacer layer 22 is made of a nonmagnetic semiconductor material, the thickness of the spacer layer 22 is preferably in the range of 1.0 to 4.0 nm.
　スペーサ層２２は、絶縁材料よりなる絶縁部と、導電材料よりなり、絶縁部中に設けられた１つ以上の通電部とを含んでいてもよい。絶縁部を構成する絶縁材料としては、Ａｌ2Ｏ3、ＭｇＯ等が挙げられる。通電部を構成する導電材料としては、ＣｏＦｅ、ＣｏＦｅＢ、ＣｏＦｅＳｉ、ＣｏＭｎＧｅ、ＣｏＭｎＳｉ、ＣｏＭｎＡｌ、Ｆｅ、Ｃｏ、Ａｕ、Ｃｕ、Ａｌ、Ｍｇ等が挙げられる。この場合、スペーサ層２２の厚みは、０．５～２．０ｎｍの範囲内であることが好ましい。 The spacer layer 22 may include an insulating portion made of an insulating material and one or more energization portions made of a conductive material and provided in the insulating portion. Examples of the insulating material constituting the insulating portion include Al 2 O 3 and MgO. Examples of the conductive material constituting the energizing portion include CoFe, CoFeB, CoFeSi, CoMnGe, CoMnSi, CoMnAl, Fe, Co, Au, Cu, Al, and Mg. In this case, the thickness of the spacer layer 22 is preferably in the range of 0.5 to 2.0 nm.
　磁化自由層２３は、強磁性材料によって構成されている。本実施の形態における磁化自由層２３は、磁化自由層２３とスペーサ層２２の界面に垂直な方向に磁化容易軸を有することが好ましい。このような磁化自由層２３は、例えば、Ｃｏ、ＣｏＣｒ系合金、ＣｏＣｒＰｔ系合金、ＦｅＰｔ系合金、希土類を含むＳｍＣｏ系合金、ＴｂＦｅＣｏ合金またはホイスラー合金よりなる膜や、Ｃｏの多層膜によって構成することができる。磁化自由層２３の厚みは、１～１０ｎｍの範囲内であることが好ましい。 The magnetization free layer 23 is made of a ferromagnetic material. The magnetization free layer 23 in the present embodiment preferably has an easy axis of magnetization in a direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22. Such a magnetization free layer 23 is made of, for example, a film made of Co, a CoCr alloy, a CoCrPt alloy, a FePt alloy, a rare earth-containing SmCo alloy, a TbFeCo alloy, or a Heusler alloy, or a Co multilayer film. Can do. The thickness of the magnetization free layer 23 is preferably in the range of 1 to 10 nm.
　磁気抵抗効果素子２は、更に、第１および第２の金属層を含んでいてもよい。第１の金属層は、磁化自由層２３と第１の電極１１の間に設けられる。第２の金属層は、磁化固定層２１と第２の電極１２の間に設けられる。第１の金属層は、キャップ層として用いられる。第２の金属層は、シード層またはバッファ層として用いられる。第１および第２の金属層は、例えば、Ｒｕ、Ｔａ、ＣｕおよびＣｒのうちの１つ以上を含む単層膜または多層膜によって構成される。第１および第２の金属層の厚みは、２～１０ｎｍの範囲内であることが好ましい。 The magnetoresistive effect element 2 may further include first and second metal layers. The first metal layer is provided between the magnetization free layer 23 and the first electrode 11. The second metal layer is provided between the magnetization fixed layer 21 and the second electrode 12. The first metal layer is used as a cap layer. The second metal layer is used as a seed layer or a buffer layer. The first and second metal layers are composed of, for example, a single layer film or a multilayer film including one or more of Ru, Ta, Cu, and Cr. The thickness of the first and second metal layers is preferably in the range of 2 to 10 nm.
　次に、図１を参照して、外部磁界印加部３の構成について説明する。外部磁界印加部３は、磁気抵抗効果素子２の近傍に配置されている。外部磁界印加部３は、電磁石を含んでいる。具体的に説明すると、外部磁界印加部３は、磁性材料よりなるコア部３２と、コア部３２に巻回されたコイル３１とを有している。コア部３２とコイル３１は、電磁石を構成している。磁気抵抗効果素子２とコア部３２は、磁化自由層２３とスペーサ層２２の界面に垂直な方向に並ぶように配置されている。本実施の形態では特に、コア部３２は、磁気抵抗効果素子２の第１の端面２ａに対向するように配置されている。 Next, the configuration of the external magnetic field application unit 3 will be described with reference to FIG. The external magnetic field application unit 3 is disposed in the vicinity of the magnetoresistive element 2. The external magnetic field application unit 3 includes an electromagnet. More specifically, the external magnetic field application unit 3 includes a core part 32 made of a magnetic material and a coil 31 wound around the core part 32. The core part 32 and the coil 31 constitute an electromagnet. The magnetoresistive effect element 2 and the core portion 32 are arranged so as to be aligned in a direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22. Particularly in the present embodiment, the core portion 32 is disposed so as to face the first end face 2 a of the magnetoresistive element 2.
　外部磁界印加部３は、更に、磁性材料よりなる第１のヨーク３３および第２のヨーク３４を有している。第１のヨーク３３は、コア部３２における磁気抵抗効果素子２とは反対側の端面に接続されている。第２のヨーク３４は、コア部３２における磁気抵抗効果素子２側の端面に対向するように配置されている。磁気抵抗効果素子２は、コア部３２と第２のヨーク３４の間に配置されている。第１のヨーク３３と第２のヨーク３４は、磁性材料よりなる図示しない第３のヨークを介して接続されていてもよい。 The external magnetic field application unit 3 further includes a first yoke 33 and a second yoke 34 made of a magnetic material. The first yoke 33 is connected to the end surface of the core portion 32 opposite to the magnetoresistive effect element 2. The second yoke 34 is disposed so as to face the end surface of the core portion 32 on the magnetoresistive effect element 2 side. The magnetoresistive element 2 is disposed between the core portion 32 and the second yoke 34. The first yoke 33 and the second yoke 34 may be connected via a third yoke (not shown) made of a magnetic material.
　本実施の形態では、外部磁界印加部３は、外部磁界の大きさを変化可能に構成されている。外部磁界の大きさは、コイル３１に流される電流の大きさを調整することによって変化させることができる。外部磁界印加部３によって変えることができる外部磁界の大きさの範囲は、例えば０～２ｋＯｅ（１Ｏｅは７９．６Ａ／ｍ）である。また、外部磁界の方向である第２の方向は、コイル３１に流される電流の方向を変えることによって、コア部３２から磁気抵抗効果素子２に向かう方向とその反対方向との間で切り替えることができる。 In the present embodiment, the external magnetic field application unit 3 is configured to be able to change the magnitude of the external magnetic field. The magnitude of the external magnetic field can be changed by adjusting the magnitude of the current flowing through the coil 31. The range of the magnitude of the external magnetic field that can be changed by the external magnetic field application unit 3 is, for example, 0 to 2 kOe (1Oe is 79.6 A / m). The second direction, which is the direction of the external magnetic field, can be switched between the direction from the core portion 32 toward the magnetoresistive effect element 2 and the opposite direction by changing the direction of the current flowing through the coil 31. it can.
　次に、図２および図３を参照して、第１および第２の方向について説明する。以下の説明では、磁化固定層２１の磁化の方向である第１の方向を記号Ｄ１で表し、磁化自由層２３に印加される外部磁界の方向である第２の方向を記号Ｄ２で表し、磁化自由層２３の磁化の方向を記号Ｄ３で表す。図２は、磁気抵抗効果素子２と第１ないし第３の方向Ｄ１，Ｄ２，Ｄ３を示している。図３は、第２の方向Ｄ２が第１の方向Ｄ１に対してなす角度を示している。 Next, the first and second directions will be described with reference to FIG. 2 and FIG. In the following description, the first direction which is the direction of magnetization of the magnetization fixed layer 21 is represented by the symbol D1, the second direction which is the direction of the external magnetic field applied to the magnetization free layer 23 is represented by the symbol D2, and the magnetization The direction of magnetization of the free layer 23 is represented by the symbol D3. FIG. 2 shows the magnetoresistive element 2 and the first to third directions D1, D2, and D3. FIG. 3 shows an angle formed by the second direction D2 with respect to the first direction D1.
　ここで、図２に示したように、Ｘ方向、Ｙ方向、Ｚ方向を定義する。Ｘ方向、Ｙ方向、Ｚ方向は、互いに直交する。本実施の形態では、磁化自由層２３とスペーサ層２２の界面に垂直な一方向（図２では上側に向かう方向）を、Ｚ方向とする。Ｘ方向とＹ方向は、いずれも、上記界面に対して平行な方向である。図２では、Ｘ方向を右側に向かう方向とし、Ｙ方向を図２における手前から奥に向かう方向としている。図３にも、図２に示したＸ，Ｙ，Ｚの各方向を示している。 Here, as shown in FIG. 2, the X direction, the Y direction, and the Z direction are defined. The X direction, the Y direction, and the Z direction are orthogonal to each other. In the present embodiment, one direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 (the direction toward the upper side in FIG. 2) is defined as the Z direction. Both the X direction and the Y direction are parallel to the interface. In FIG. 2, the X direction is a direction toward the right side, and the Y direction is a direction from the near side to the back side in FIG. FIG. 3 also shows the X, Y, and Z directions shown in FIG.
　本実施の形態では、第１の方向Ｄ１と第２の方向Ｄ２のうちの少なくとも第２の方向Ｄ２は、磁化自由層２３とスペーサ層２２の界面と交差する方向である。本実施の形態では特に、第２の方向Ｄ２は、上記界面に垂直な方向であり、Ｚ方向と一致する。これを実現するために、本実施の形態では、磁気抵抗効果素子２と外部磁界印加部３のコア部３２（図１参照）が、Ｚ方向に並ぶように配置されている。図２は、磁化自由層２３の磁化の方向Ｄ３が、第２の方向Ｄ２（Ｚ方向）と一致している状態を示している。 In the present embodiment, at least the second direction D2 of the first direction D1 and the second direction D2 is a direction intersecting the interface between the magnetization free layer 23 and the spacer layer 22. Particularly in the present embodiment, the second direction D2 is a direction perpendicular to the interface and coincides with the Z direction. In order to realize this, in the present embodiment, the magnetoresistive effect element 2 and the core portion 32 (see FIG. 1) of the external magnetic field application unit 3 are arranged in the Z direction. FIG. 2 shows a state in which the magnetization direction D3 of the magnetization free layer 23 coincides with the second direction D2 (Z direction).
　図３に示したように、第２の方向Ｄ２が第１の方向Ｄ１に対してなす角度を、記号θで表す。角度θは、９０°～１５０°の範囲内である。角度θは、１０５°～１３５°の範囲内であることが好ましい。角度θが９０°の場合には、第１の方向Ｄ１は磁化自由層２３とスペーサ層２２の界面に平行な方向である。角度θが９０°よりも大きく１５０°以下の場合には、第１の方向Ｄ１は、磁化自由層２３とスペーサ層２２の界面と交差する方向である。第１の方向Ｄ１は、例えば、磁界中熱処理によって磁化固定層２１の磁化の方向を設定する際の磁界の方向を変えることによって、容易に任意の方向に設定することができる。また、本実施の形態では、前述の通り、第２の方向Ｄ２は、磁化自由層２３とスペーサ層２２の界面に垂直な方向である。これにより、第２の方向Ｄ２の外部磁界を、容易に且つ精度よく磁化自由層２３に印加することが可能になる。 As shown in FIG. 3, the angle formed by the second direction D2 with respect to the first direction D1 is represented by the symbol θ. The angle θ is in the range of 90 ° to 150 °. The angle θ is preferably in the range of 105 ° to 135 °. When the angle θ is 90 °, the first direction D1 is a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22. When the angle θ is greater than 90 ° and equal to or less than 150 °, the first direction D1 is a direction intersecting the interface between the magnetization free layer 23 and the spacer layer 22. The first direction D1 can be easily set to an arbitrary direction, for example, by changing the direction of the magnetic field when setting the magnetization direction of the magnetization fixed layer 21 by heat treatment in a magnetic field. In the present embodiment, as described above, the second direction D2 is a direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22. Thereby, the external magnetic field in the second direction D2 can be easily and accurately applied to the magnetization free layer 23.
　次に、本実施の形態に係る共振器１の作用および効果について説明する。本実施の形態では、磁気抵抗効果素子２の磁化自由層２３の強磁性共鳴周波数と等しい周波数で変動するエネルギを磁気抵抗効果素子２に付与することによって、磁化自由層２３に強磁性共鳴を生じさせることができる。 Next, functions and effects of the resonator 1 according to the present embodiment will be described. In the present embodiment, by applying energy that varies at a frequency equal to the ferromagnetic resonance frequency of the magnetization free layer 23 of the magnetoresistive effect element 2 to the magnetoresistive effect element 2, ferromagnetic resonance occurs in the magnetization free layer 23. Can be made.
　本実施の形態では特に、上記エネルギとして、高周波電流を用いる。高周波電流は、磁気抵抗効果素子２を流れる直流電流に重畳されて、磁気抵抗効果素子２に付与される。高周波電流が磁気抵抗効果素子２に付与されると、磁化自由層２３における電流密度が高周波電流の周波数で変化し、その結果、磁化自由層２３の磁化に作用するスピントランスファートルクが、高周波電流の周波数で変化する。スピントランスファートルクとは、スピン流の流入または流出が生じた強磁性体において、スピン流の変化分におけるスピン角運動量の変化と逆方向に強磁性体の磁化を回転させるように強磁性体の磁化に作用するトルクである。従って、磁化自由層２３において、スピントランスファートルクが高周波電流の周波数で変化すると、磁化自由層２３の磁化は、その方向が変化するように、高周波電流の周波数で振動する。 Particularly in this embodiment, a high-frequency current is used as the energy. The high frequency current is superimposed on the direct current flowing through the magnetoresistive effect element 2 and applied to the magnetoresistive effect element 2. When a high-frequency current is applied to the magnetoresistive effect element 2, the current density in the magnetization free layer 23 changes with the frequency of the high-frequency current, and as a result, the spin transfer torque that acts on the magnetization of the magnetization free layer 23 causes the high-frequency current to Varies with frequency. Spin transfer torque refers to the magnetization of a ferromagnet so that the magnetization of the ferromagnet rotates in the direction opposite to the change of the spin angular momentum in the change of the spin current in the ferromagnet in which the inflow or outflow of the spin current occurs. Is the torque acting on the. Therefore, in the magnetization free layer 23, when the spin transfer torque changes at the frequency of the high frequency current, the magnetization of the magnetization free layer 23 oscillates at the frequency of the high frequency current so that its direction changes.
　磁気抵抗効果素子２は、磁化自由層２３の磁化の振動に起因する高周波出力信号を生成する。この高周波出力信号の周波数は、高周波入力信号の周波数と等しい。高周波出力信号は、第２の信号線路７によって、磁気抵抗効果素子２から出力ポート８に伝送される。出力ポート８には、この高周波出力信号が現れる。 The magnetoresistive effect element 2 generates a high frequency output signal resulting from the vibration of magnetization of the magnetization free layer 23. The frequency of the high frequency output signal is equal to the frequency of the high frequency input signal. The high frequency output signal is transmitted from the magnetoresistive effect element 2 to the output port 8 by the second signal line 7. This high frequency output signal appears at the output port 8.
　より具体的に説明すると、磁化自由層２３の磁化が振動すると、磁化自由層２３の磁化の方向Ｄ３が磁化固定層２１の磁化の方向Ｄ１に対してなす角度が変化し、その結果、磁気抵抗効果素子２の抵抗値が変化する。高周波出力信号は、この磁気抵抗効果素子２の抵抗値の変化によって生成される。本実施の形態では特に、高周波出力信号は、出力ポート８の端子８１の電位の変化として現れる。 More specifically, when the magnetization of the magnetization free layer 23 vibrates, the angle formed by the magnetization direction D3 of the magnetization free layer 23 with respect to the magnetization direction D1 of the magnetization fixed layer 21 changes, and as a result, the magnetoresistance The resistance value of the effect element 2 changes. A high frequency output signal is generated by a change in the resistance value of the magnetoresistive element 2. Particularly in this embodiment, the high-frequency output signal appears as a change in the potential of the terminal 81 of the output port 8.
　高周波入力信号の周波数が磁化自由層２３の強磁性共鳴周波数と等しい場合には、磁化自由層２３において強磁性共鳴が生じて、磁化自由層２３の磁化の振動の振幅が最大になる。その結果、高周波出力信号の振幅も最大になる。 When the frequency of the high frequency input signal is equal to the ferromagnetic resonance frequency of the magnetization free layer 23, ferromagnetic resonance occurs in the magnetization free layer 23, and the amplitude of magnetization vibration of the magnetization free layer 23 is maximized. As a result, the amplitude of the high frequency output signal is also maximized.
　磁化自由層２３の強磁性共鳴周波数は、例えば、磁化自由層２３に作用する有効磁界の大きさを変化させることによって変化させることができる。本実施の形態では、磁化自由層２３に作用する有効磁界の大きさは、外部磁界印加部３によって磁化自由層２３に印加される外部磁界の大きさに依存する。従って、本実施の形態では、磁化自由層２３の強磁性共鳴周波数は、例えば、磁化自由層２３に印加される外部磁界の大きさを変化させることによって変化させることができる。具体的に説明すると、外部磁界を大きくすると強磁性共鳴周波数は高くなる。 The ferromagnetic resonance frequency of the magnetization free layer 23 can be changed by changing the magnitude of the effective magnetic field acting on the magnetization free layer 23, for example. In the present embodiment, the magnitude of the effective magnetic field acting on the magnetization free layer 23 depends on the magnitude of the external magnetic field applied to the magnetization free layer 23 by the external magnetic field application unit 3. Therefore, in the present embodiment, the ferromagnetic resonance frequency of the magnetization free layer 23 can be changed, for example, by changing the magnitude of the external magnetic field applied to the magnetization free layer 23. More specifically, the ferromagnetic resonance frequency increases when the external magnetic field is increased.
　また、本実施の形態では、第２の方向Ｄ２が第１の方向Ｄ１に対してなす角度θを、９０°～１５０°の範囲内の角度としている。これにより、磁化自由層２３に強磁性共鳴を生じさせたときの磁気抵抗効果素子２の抵抗値の変化量が十分に大きくなる。その結果、高周波出力信号の振幅が十分に大きくなり、磁気抵抗効果素子２を用いた実用的な共振器１を実現することが可能になる。 In the present embodiment, the angle θ formed by the second direction D2 with respect to the first direction D1 is an angle in the range of 90 ° to 150 °. Thereby, the amount of change in the resistance value of the magnetoresistive effect element 2 when ferromagnetic resonance is generated in the magnetization free layer 23 becomes sufficiently large. As a result, the amplitude of the high-frequency output signal becomes sufficiently large, and a practical resonator 1 using the magnetoresistive effect element 2 can be realized.
　以下、角度θを９０°～１５０°の範囲内の角度とする理由について、シミュレーションの結果を参照して説明する。ここで、磁化固定層２１の磁化の方向である第１の方向Ｄ１と磁化自由層２３の磁化の方向Ｄ３が一致している状態における磁気抵抗効果素子２の抵抗値をＲｐとし、磁化自由層２３の磁化の振動に伴う磁気抵抗効果素子２の抵抗値の変化量の最大値をΔＲとしたとき、磁化自由層２３の磁化の振動に伴う磁気抵抗効果素子２の抵抗変化率をΔＲ／Ｒｐと定義する。抵抗変化率ΔＲ／Ｒｐは、ΔＲに比例する。 Hereinafter, the reason why the angle θ is set in the range of 90 ° to 150 ° will be described with reference to the simulation results. Here, the resistance value of the magnetoresistive effect element 2 in a state where the first direction D1 which is the magnetization direction of the magnetization fixed layer 21 and the magnetization direction D3 of the magnetization free layer 23 coincide with each other is Rp, and the magnetization free layer When the maximum value of the change amount of the resistance value of the magnetoresistive effect element 2 due to the magnetization vibration of 23 is ΔR, the rate of change in resistance of the magnetoresistive effect element 2 due to the magnetization vibration of the magnetization free layer 23 is ΔR / Rp It is defined as The resistance change rate ΔR / Rp is proportional to ΔR.
　シミュレーションでは、磁化自由層２３の強磁性共鳴周波数と等しい周波数の高周波入力信号に基づく高周波電流を磁気抵抗効果素子２に付与したときの、角度θと抵抗変化率ΔＲ／Ｒｐとの関係を求めた。磁化自由層２３の強磁性共鳴周波数と高周波入力信号の周波数は、０．３ＧＨｚ～２．８ＧＨｚの範囲内で変化させた。磁化自由層２３の強磁性共鳴周波数は、磁化自由層２３に作用する有効磁界の大きさを調整することによって変化させた。 In the simulation, the relationship between the angle θ and the resistance change rate ΔR / Rp when a high-frequency current based on a high-frequency input signal having a frequency equal to the ferromagnetic resonance frequency of the magnetization free layer 23 is applied to the magnetoresistive effect element 2 was obtained. . The ferromagnetic resonance frequency of the magnetization free layer 23 and the frequency of the high frequency input signal were changed within the range of 0.3 GHz to 2.8 GHz. The ferromagnetic resonance frequency of the magnetization free layer 23 was changed by adjusting the magnitude of the effective magnetic field acting on the magnetization free layer 23.
　図４に、シミュレーションの結果を示す。図４において、横軸は角度θを示し、縦軸は抵抗変化率ΔＲ／Ｒｐを示している。図４から、抵抗変化率ΔＲ／Ｒｐは、角度θに対して、以下のような依存性を有することが分かる。まず、抵抗変化率ΔＲ／Ｒｐは、角度θが１２０°またはその近傍の角度のときに最大になる。また、抵抗変化率ΔＲ／Ｒｐは、角度θがおよそ９０°～１５０°の範囲内の場合に、角度θがその範囲外の場合に比べて、相対的に大きくなる。また、抵抗変化率ΔＲ／Ｒｐは、角度θがおよそ１０５°～１３５°の範囲内の場合に、角度θがその範囲外の場合に比べて、相対的に顕著に大きくなる。 Figure 4 shows the simulation results. In FIG. 4, the horizontal axis represents the angle θ, and the vertical axis represents the resistance change rate ΔR / Rp. FIG. 4 shows that the resistance change rate ΔR / Rp has the following dependence on the angle θ. First, the resistance change rate ΔR / Rp becomes maximum when the angle θ is 120 ° or an angle in the vicinity thereof. The resistance change rate ΔR / Rp is relatively large when the angle θ is in the range of approximately 90 ° to 150 °, compared to when the angle θ is out of the range. In addition, the resistance change rate ΔR / Rp is relatively remarkably increased when the angle θ is in the range of about 105 ° to 135 °, compared to the case where the angle θ is out of the range.
　ΔＲは、磁化自由層２３に強磁性共鳴を生じさせたときの磁気抵抗効果素子２の抵抗値の変化量に対応する。上述の抵抗変化率ΔＲ／Ｒｐの角度θに対する依存性から、磁化自由層２３に強磁性共鳴を生じさせたときの磁気抵抗効果素子２の抵抗値の変化量を十分に大きくするためには、角度θは、９０°～１５０°の範囲内であることが好ましく、１０５°～１３５°の範囲内であることがより好ましいと言える。そこで、本実施の形態では、角度θを、９０°～１５０°の範囲内、好ましくは１０５°～１３５°の範囲内の角度にしている。 ΔR corresponds to the amount of change in the resistance value of the magnetoresistive element 2 when ferromagnetic resonance is caused in the magnetization free layer 23. In order to sufficiently increase the amount of change in the resistance value of the magnetoresistive element 2 when ferromagnetic resonance is caused in the magnetization free layer 23 from the dependence of the resistance change rate ΔR / Rp on the angle θ, The angle θ is preferably in the range of 90 ° to 150 °, and more preferably in the range of 105 ° to 135 °. Therefore, in the present embodiment, the angle θ is set to an angle within the range of 90 ° to 150 °, preferably within the range of 105 ° to 135 °.
　図５は、角度θを１２０°にしたときの、共振器１の通過特性の一例を示している。ここでは、共振器１の通過特性を、高周波入力信号の電力に対する高周波出力信号の電力の比を表すＳパラメータＳ２１を用いて表す。図５において、横軸は周波数を示し、縦軸はｄＢ単位で表したＳパラメータＳ２１を示している。ｄＢ単位で表したＳパラメータＳ２１の値を－ＩｄＢと表したとき、Ｉの値が小さいほど、高周波入力信号の電力に対する高周波出力信号の電力の比が大きい。図５に示した例では、磁化自由層２３の強磁性共鳴周波数を、３．０７ＧＨｚとした。図５から、高周波入力信号の周波数が磁化自由層２３の強磁性共鳴周波数と等しいときに、Ｉの値が最も小さくなることが分かる。図５は、共振器１が、十分に実用的な共振器の機能を有することを示している。磁化自由層２３の強磁性共鳴周波数は、共振器１の共振周波数に対応する。 FIG. 5 shows an example of the pass characteristic of the resonator 1 when the angle θ is 120 °. Here, the pass characteristic of the resonator 1 is expressed using an S parameter S21 that represents the ratio of the power of the high-frequency output signal to the power of the high-frequency input signal. In FIG. 5, the horizontal axis indicates the frequency, and the vertical axis indicates the S parameter S21 expressed in dB. When the value of the S parameter S21 expressed in dB is expressed as -Id, the smaller the value of I, the larger the ratio of the power of the high frequency output signal to the power of the high frequency input signal. In the example shown in FIG. 5, the ferromagnetic resonance frequency of the magnetization free layer 23 is set to 3.07 GHz. FIG. 5 shows that the value of I is the smallest when the frequency of the high-frequency input signal is equal to the ferromagnetic resonance frequency of the magnetization free layer 23. FIG. 5 shows that the resonator 1 has a sufficiently practical resonator function. The ferromagnetic resonance frequency of the magnetization free layer 23 corresponds to the resonance frequency of the resonator 1.
　本実施の形態によれば、例えば磁化自由層２３に印加される外部磁界の大きさを変えることによって、共振器１の共振周波数に対応する磁化自由層２３の強磁性共鳴周波数を変えることができる。そのため、本実施の形態に係る共振器１は、共振周波数が異なる複数の用途に使用することが可能である。 According to the present embodiment, for example, the ferromagnetic resonance frequency of the magnetization free layer 23 corresponding to the resonance frequency of the resonator 1 can be changed by changing the magnitude of the external magnetic field applied to the magnetization free layer 23. . Therefore, the resonator 1 according to the present embodiment can be used for a plurality of applications having different resonance frequencies.
　以下、角度θを９０°～１５０°の範囲内の角度にすることによって、磁化自由層２３に強磁性共鳴を生じさせたときの磁気抵抗効果素子２の抵抗値の変化量が十分に大きくなる理由について説明する。始めに、図６を参照して、磁化自由層２３の磁化の挙動について説明する。以下の説明では、磁化固定層２１の磁化を記号Ｍ1で表し、磁化自由層２３の磁化を記号Ｍ2で表し、磁化自由層２３の磁化Ｍ2に作用する有効磁界を記号Ｈeffで表す。図６は、磁化Ｍ1，Ｍ2と有効磁界Ｈeffのそれぞれの方向を示している。磁化自由層２３の磁化Ｍ2の挙動は、ＬＬＧ（Landau Lifshitz Gilbert）方程式を用いて、下記の式（１）によって表される。 Hereinafter, by setting the angle θ to an angle within the range of 90 ° to 150 °, the amount of change in the resistance value of the magnetoresistive effect element 2 when the ferromagnetic resonance is generated in the magnetization free layer 23 becomes sufficiently large. The reason will be explained. First, the magnetization behavior of the magnetization free layer 23 will be described with reference to FIG. In the following description, the magnetization of the magnetization fixed layer 21 is represented by the symbol M 1 , the magnetization of the magnetization free layer 23 is represented by the symbol M 2 , and the effective magnetic field acting on the magnetization M 2 of the magnetization free layer 23 is represented by the symbol H eff . . FIG. 6 shows the directions of the magnetizations M 1 and M 2 and the effective magnetic field H eff . The behavior of the magnetization M 2 of the magnetization free layer 23 is expressed by the following formula (1) using an LLG (Landau Lifshitz Gilbert) equation.
　∂Ｍ2／∂ｔ＝－|γ|（Ｍ2×Ｈeff）
　　　　　　　 －|γ|αｍ2×（Ｍ2×Ｈeff）
　　　　　　　　＋ｇβＩeｍ2×（ｍ2×ｍ1）　　…（１） ∂M 2 / ∂t = − | γ | (M 2 × H eff )
− | Γ | αm 2 × (M 2 × H eff )
+ GβI e m 2 × (m 2 × m 1 ) (1)
　式（１）の第１項、第２項、第３項は、それぞれ、歳差トルク、ダンピングトルク、スピントランスファートルクを表している。図６において、記号Ｔ１を付した矢印は歳差トルクを表し、記号Ｔ２を付した矢印はダンピングトルクを表し、記号Ｔ３を付した矢印はスピントランスファートルクを表している。 The first term, the second term, and the third term of Equation (1) represent precession torque, damping torque, and spin transfer torque, respectively. In FIG. 6, the arrow with the symbol T1 represents the precession torque, the arrow with the symbol T2 represents the damping torque, and the arrow with the symbol T3 represents the spin transfer torque.
　式（１）におけるｍ1，ｍ2は、それぞれ、磁化Ｍ1，Ｍ2の方向の単位ベクトルである。また、γはジャイロ磁気定数であり、αはダンピング定数であり、Ｉeは電流密度である。また、βは、ディラック定数すなわち換算プランク定数を、２ｅ（ｅは電荷）で割った値である。また、ｇは、スピントランスファーの効率を表すパラメータである。ｇは、スピン分極率Ｐと、磁化Ｍ2の方向が磁化Ｍ1の方向に対してなす角度φ（図６参照）を用いて、下記の式（２）によって表される。 M 1, m 2 in the formula (1), respectively, it is a unit vector in the direction of the magnetization M 1, M 2. Γ is a gyro magnetic constant, α is a damping constant, and I e is a current density. Further, β is a value obtained by dividing the Dirac constant, that is, the converted Planck constant by 2e (e is electric charge). G is a parameter representing the efficiency of spin transfer. g is expressed by the following formula (2) using the spin polarizability P and the angle φ (see FIG. 6) formed by the direction of the magnetization M 2 with respect to the direction of the magnetization M 1 .
　ｇ＝Ｐ／（１＋Ｐ2ｃｏｓφ）　　…（２） g = P / (1 + P 2 cos φ) (2)
　次に、角度φとスピントランスファートルクの大きさとの関係について説明する。式（１）におけるｍ2×（ｍ2×ｍ1）の大きさは、ｓｉｎφと表される。式（１）から、スピントランスファートルクの大きさは、ｇ・ｓｉｎφに比例する。ｇ・ｓｉｎφは、スピントランスファートルクの大きさを決めるパラメータと言える。 Next, the relationship between the angle φ and the magnitude of the spin transfer torque will be described. The size of m 2 × in the formula (1) (m 2 × m 1) is expressed as sin [phi. From equation (1), the magnitude of the spin transfer torque is proportional to g · sinφ. g · sinφ can be said to be a parameter that determines the magnitude of the spin transfer torque.
　図７は、角度φを変化させたときのｇ・ｓｉｎφの変化を示す特性図である。図７において、横軸は角度φを示し、縦軸はｇ・ｓｉｎφの値を示している。図７において、符号９１，９２，９３，９４を付した曲線は、それぞれ、スピン分極率Ｐを０．４、０．５、０．６、０．７としたときのｇ・ｓｉｎφを示している。実用的なスピン分極率Ｐは、例えば０．５～０．７の範囲内である。図７から、スピン分極率Ｐが０．５～０．７の範囲内である場合には、ｇ・ｓｉｎφが最大になるとき、すなわちスピントランスファートルクが最大になるときの角度φは、およそ１０５°～１２０°の範囲内であることが分かる。 FIG. 7 is a characteristic diagram showing changes in g · sin φ when the angle φ is changed. In FIG. 7, the horizontal axis indicates the angle φ, and the vertical axis indicates the value of g · sin φ. In FIG. 7, the curves denoted by reference numerals 91, 92, 93, and 94 indicate g · sin φ when the spin polarizability P is 0.4, 0.5, 0.6, and 0.7, respectively. Yes. The practical spin polarizability P is, for example, in the range of 0.5 to 0.7. From FIG. 7, when the spin polarizability P is in the range of 0.5 to 0.7, the angle φ when g · sin φ becomes maximum, that is, when the spin transfer torque becomes maximum, is about 105. It can be seen that it is within the range of ° to 120 °.
　本実施の形態では、有効磁界Ｈeffの方向は、外部磁界の方向である第２の方向Ｄ２と一致するか、ほぼ一致する。磁化自由層２３の磁化Ｍ2の方向Ｄ３が第２の方向Ｄ２と一致している状態では、磁化自由層２３の磁化Ｍ2の方向Ｄ３は、有効磁界Ｈeffの方向と一致するか、ほぼ一致する。この状態では、図６に示した角度φは、図３に示した角度θと一致するか、ほぼ一致する。従って、この状態では、角度θが、およそ１０５°～１２０°の範囲内であるときに、磁化自由層２３の磁化Ｍ2に作用するスピントランスファートルクが最大になる。 In the present embodiment, the direction of the effective magnetic field H eff coincides with or substantially coincides with the second direction D2, which is the direction of the external magnetic field. Or direction D3 of the magnetization M 2 of the magnetization free layer 23 is in the state to match the second direction D2, the direction D3 of the magnetization M 2 of the magnetization free layer 23 coincides with the direction of the effective magnetic field H eff, approximately Match. In this state, the angle φ shown in FIG. 6 matches or substantially matches the angle θ shown in FIG. Therefore, in this state, the spin transfer torque acting on the magnetization M 2 of the magnetization free layer 23 is maximized when the angle θ is in the range of approximately 105 ° to 120 °.
　一方、磁化自由層２３の磁化Ｍ2に作用するスピントランスファートルクが大きいほど、高周波電流を用いて、効率よくエネルギを磁気抵抗効果素子２に付与することができる。 On the other hand, as the spin transfer torque acting on the magnetization M 2 of the magnetization free layer 23 increases, energy can be efficiently applied to the magnetoresistive effect element 2 using a high-frequency current.
　これらのことから、図７に示したｇ・ｓｉｎφの角度φに対する依存性が、図４に示した抵抗変化率ΔＲ／Ｒｐの角度θに対する依存性を生じさせる一因であると考えられる。 From these facts, it is considered that the dependency of g · sin φ on the angle φ shown in FIG. 7 is one of the causes for the dependency of the resistance change rate ΔR / Rp on the angle θ shown in FIG.
　ところで、本実施の形態では、磁気抵抗効果素子２に直流電流が供給され、この直流電流によって、磁化固定層２１から磁化自由層２３に向かうスピン流が生じる。以下、この直流電流によるスピン流が抵抗変化率ΔＲ／Ｒｐに与える影響について説明する。この直流電流によるスピン流は、磁化自由層２３の磁化Ｍ2に対して、図６に示した角度φを小さくするようなスピントランスファートルクを与える。以下、このスピントランスファートルクを、直流起因スピントランスファートルクと言う。 By the way, in the present embodiment, a direct current is supplied to the magnetoresistive effect element 2, and a spin flow from the magnetization fixed layer 21 to the magnetization free layer 23 is generated by this direct current. Hereinafter, the influence of the spin current due to the direct current on the resistance change rate ΔR / Rp will be described. The spin current caused by the direct current gives a spin transfer torque that reduces the angle φ shown in FIG. 6 to the magnetization M 2 of the magnetization free layer 23. Hereinafter, this spin transfer torque is referred to as direct current-induced spin transfer torque.
　ここで、磁化自由層２３の磁化Ｍ2の振動の中心軸が、磁化固定層２１の磁化Ｍ1の方向すなわち第１の方向Ｄ１に対してなす角度を記号θｃで表す。本実施の形態のように第２の方向Ｄ２が第１の方向Ｄ１に対してなす角度θが１８０°よりも小さい場合において、直流起因スピントランスファートルクが磁化自由層２３の磁化Ｍ2に作用すると、角度θｃは、有効磁界Ｈeffの方向が第１の方向Ｄ１に対してなす角度よりもいくらか小さくなる。本実施の形態では、有効磁界Ｈeffの方向は、外部磁界の方向である第２の方向Ｄ２と一致するか、ほぼ一致する。従って、本実施の形態では、角度θｃは、図３に示した角度θよりもいくらか小さくなる。 Here, the angle formed by the central axis of the vibration of the magnetization M 2 of the magnetization free layer 23 with respect to the direction of the magnetization M 1 of the magnetization fixed layer 21, that is, the first direction D 1 is represented by the symbol θc. When the angle θ formed by the second direction D2 with respect to the first direction D1 is smaller than 180 ° as in the present embodiment, the direct current-induced spin transfer torque acts on the magnetization M 2 of the magnetization free layer 23. The angle θc is somewhat smaller than the angle formed by the direction of the effective magnetic field H eff with respect to the first direction D1. In the present embodiment, the direction of the effective magnetic field H eff coincides with or substantially coincides with the second direction D2, which is the direction of the external magnetic field. Therefore, in the present embodiment, the angle θc is somewhat smaller than the angle θ shown in FIG.
　磁化自由層２３の磁化Ｍ2の振動の振幅が一定であると仮定すると、角度θｃが９０°のときに、抵抗変化率ΔＲ／Ｒｐが最大になる。本実施の形態において、直流起因スピントランスファートルクが磁化自由層２３の磁化Ｍ2に作用する場合には、角度θを９０°にすると角度θｃは９０°よりも小さくなる。本実施の形態において、直流起因スピントランスファートルクが磁化自由層２３の磁化Ｍ2に作用する場合には、角度θを９０°よりもいくらか大きくした方が、角度θを９０°にした場合に比べて、角度θｃを９０°に近づけて、抵抗変化率ΔＲ／Ｒｐを大きくすることが可能になる。 Assuming that the amplitude of vibration of the magnetization M 2 of the magnetization free layer 23 is constant, the resistance change rate ΔR / Rp becomes maximum when the angle θc is 90 °. In the present embodiment, when the direct current-induced spin transfer torque acts on the magnetization M 2 of the magnetization free layer 23, when the angle θ is 90 °, the angle θc is smaller than 90 °. In the present embodiment, when the DC-induced spin transfer torque acts on the magnetization M 2 of the magnetization free layer 23, the angle θ is somewhat larger than 90 ° compared to the angle θ being 90 °. Thus, the resistance change rate ΔR / Rp can be increased by making the angle θc close to 90 °.
　従って、本実施の形態において、直流起因スピントランスファートルクが磁化自由層２３の磁化Ｍ2に作用する場合には、角度θは、９０°よりも大きく１５０°以下であることが好ましく、１０５°～１３５°の範囲内であることがより好ましい。 Therefore, in the present embodiment, when the direct current-induced spin transfer torque acts on the magnetization M 2 of the magnetization free layer 23, the angle θ is preferably greater than 90 ° and equal to or less than 150 °, and is 105 ° to More preferably, it is within the range of 135 °.
　ここで、第１の方向Ｄ１と同じ方向の単位ベクトルを第１の単位ベクトルとし、第２の方向Ｄ２と同じ方向の単位ベクトルを第２の単位ベクトルとする。共振器１に関して、磁化自由層２３とスペーサ層２２の界面に垂直または平行な平面であって、その平面における第２の単位ベクトルの成分が第１の単位ベクトルの成分に対してなす角度が９０°～１５０°好ましくは１０５°～１３５°となる平面が存在していてもよい。以下、このような平面を基準平面と言う。基準平面は、第１の方向Ｄ１および第２の方向Ｄ２に平行であることが好ましい。この場合には、基準平面における第２の単位ベクトルの成分が第１の単位ベクトルの成分に対してなす角度は、角度θと等しい。この場合、第１の方向Ｄ１おと第２の方向Ｄ２の関係を容易に把握することが可能になる。本実施の形態では、少なくとも、磁化自由層２３とスペーサ層２２の界面に垂直なＸＺ平面が基準平面に該当する。 Here, a unit vector in the same direction as the first direction D1 is defined as a first unit vector, and a unit vector in the same direction as the second direction D2 is defined as a second unit vector. Regarding the resonator 1, a plane perpendicular to or parallel to the interface between the magnetization free layer 23 and the spacer layer 22, and the angle formed by the component of the second unit vector and the component of the first unit vector in the plane is 90 There may be a flat surface at an angle of from 150 ° to 150 °, preferably from 105 ° to 135 °. Hereinafter, such a plane is referred to as a reference plane. The reference plane is preferably parallel to the first direction D1 and the second direction D2. In this case, the angle formed by the component of the second unit vector on the reference plane with respect to the component of the first unit vector is equal to the angle θ. In this case, it is possible to easily grasp the relationship between the first direction D1 and the second direction D2. In the present embodiment, at least the XZ plane perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 corresponds to the reference plane.
［第２の実施の形態］
　次に、本発明の第２の実施の形態について説明する。始めに、図８を参照して、本実施の形態に係る共振器１の構成について説明する。本実施の形態に係る共振器１の構成は、以下の点で第１の実施の形態と異なっている。本実施の形態に係る共振器１は、第１の実施の形態における外部磁界印加部３の代わりに、外部磁界印加部１０３を備えている。外部磁界印加部１０３は、磁気抵抗効果素子２の近傍に配置されている。 [Second Embodiment]
Next, a second embodiment of the present invention will be described. First, the configuration of the resonator 1 according to the present embodiment will be described with reference to FIG. The configuration of the resonator 1 according to the present embodiment is different from that of the first embodiment in the following points. The resonator 1 according to the present embodiment includes an external magnetic field application unit 103 instead of the external magnetic field application unit 3 in the first embodiment. The external magnetic field application unit 103 is disposed in the vicinity of the magnetoresistive element 2.
　外部磁界印加部１０３は、第１および第２の電磁石を含んでいる。具体的に説明すると、外部磁界印加部１０３は、それぞれ磁性材料よりなる第１のコア部１３２および第２のコア部１３３と、導線１３１とを有している。導線１３１は、第１のコア部１３２に巻回された第１の巻線部分と、第２のコア部１３３に巻回された第２の巻線部分とを含んでいる。第１の巻線部分と第２の巻線部分は、直列に接続されている。第１のコア部１３２と第１の巻線部分は、第１の電磁石を構成している。第２のコア部１３３と第２の巻線部分は、第２の電磁石を構成している。第１および第２のコア部１３２，１３３は、磁気抵抗効果素子２の磁化自由層２３とスペーサ層２２の界面に平行な方向における磁気抵抗効果素子２の両側に配置されている。 External magnetic field application unit 103 includes first and second electromagnets. More specifically, the external magnetic field application unit 103 includes a first core unit 132 and a second core unit 133 each made of a magnetic material, and a conducting wire 131. The conductive wire 131 includes a first winding portion wound around the first core portion 132 and a second winding portion wound around the second core portion 133. The first winding portion and the second winding portion are connected in series. The first core portion 132 and the first winding portion constitute a first electromagnet. The second core portion 133 and the second winding portion constitute a second electromagnet. The first and second core portions 132 and 133 are arranged on both sides of the magnetoresistive element 2 in a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 of the magnetoresistive element 2.
　外部磁界印加部１０３は、磁気抵抗効果素子２の磁化自由層２３に対して、第２の方向Ｄ２の外部磁界を印加する。本実施の形態では、外部磁界印加部１０３は、外部磁界の大きさを変化可能に構成されている。外部磁界の大きさは、導線１３１に流される電流の大きさを調整することによって変化させることができる。また、第２の方向Ｄ２は、導線１３１に流される電流の方向を変えることによって、コア部１３２からコア部１３３に向かう方向とその反対方向との間で切り替えることができる。 The external magnetic field application unit 103 applies an external magnetic field in the second direction D2 to the magnetization free layer 23 of the magnetoresistive effect element 2. In the present embodiment, the external magnetic field application unit 103 is configured to be able to change the magnitude of the external magnetic field. The magnitude of the external magnetic field can be changed by adjusting the magnitude of the current flowing through the conducting wire 131. Further, the second direction D2 can be switched between the direction from the core part 132 toward the core part 133 and the opposite direction by changing the direction of the current flowing through the conducting wire 131.
　第１の実施の形態と同様に、磁化固定層２１は、第１の方向Ｄ１の磁化を有する第１の磁性層のみからなる。以下、本実施の形態における第１および第２の方向Ｄ１，Ｄ２の、第１の例と第２の例について説明する。 As in the first embodiment, the magnetization fixed layer 21 is composed of only the first magnetic layer having the magnetization in the first direction D1. Hereinafter, a first example and a second example of the first and second directions D1 and D2 in the present embodiment will be described.
　始めに、図９を参照して、本実施の形態における第１および第２の方向Ｄ１，Ｄ２の第１の例について説明する。図９には、第１の実施の形態における図２に示したＸ，Ｙ，Ｚの各方向も示している。図９では、Ｙ方向を図９における手前から奥に向かう方向としている。 First, a first example of the first and second directions D1 and D2 in the present embodiment will be described with reference to FIG. FIG. 9 also shows the X, Y, and Z directions shown in FIG. 2 in the first embodiment. In FIG. 9, the Y direction is the direction from the near side to the back side in FIG.
　第１の例では、第２の方向Ｄ２は、磁化自由層２３とスペーサ層２２の界面に平行な方向であり、Ｘ方向と一致する。これを実現するために、本実施の形態では、図８に示したように、コア部１３２、磁気抵抗効果素子２およびコア部１３３が、Ｘ方向に並ぶように配置されている。図９は、磁化自由層２３の磁化の方向Ｄ３が、第２の方向Ｄ２（Ｘ方向）と一致している状態を示している。 In the first example, the second direction D2 is a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 and coincides with the X direction. In order to realize this, in the present embodiment, as shown in FIG. 8, the core part 132, the magnetoresistive effect element 2, and the core part 133 are arranged so as to be aligned in the X direction. FIG. 9 shows a state in which the magnetization direction D3 of the magnetization free layer 23 coincides with the second direction D2 (X direction).
　また、第１の例では、第１の方向Ｄ１は、磁化自由層２３とスペーサ層２２の界面と交差する方向である。第２の方向Ｄ２が第１の方向Ｄ１に対してなす角度θの範囲は、第１の実施の形態と同じである。第１の例では、少なくとも、磁化自由層２３とスペーサ層２２の界面に垂直なＸＺ平面が、第１の実施の形態で定義した基準平面に該当する。 In the first example, the first direction D1 is a direction intersecting the interface between the magnetization free layer 23 and the spacer layer 22. The range of the angle θ formed by the second direction D2 with respect to the first direction D1 is the same as that in the first embodiment. In the first example, at least the XZ plane perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 corresponds to the reference plane defined in the first embodiment.
　次に、図１０を参照して、本実施の形態における第１および第２の方向Ｄ１，Ｄ２の第２の例について説明する。図１０には、Ｘ，Ｙ，Ｚの各方向も示している。 Next, a second example of the first and second directions D1 and D2 in the present embodiment will be described with reference to FIG. FIG. 10 also shows X, Y, and Z directions.
　第２の例では、第２の方向Ｄ２は、第１の例と同様に、磁化自由層２３とスペーサ層２２の界面に平行な方向であり、Ｘ方向と一致する。図１０は、磁化自由層２３の磁化の方向Ｄ３が、第２の方向Ｄ２（Ｘ方向）と一致している状態を示している。また、第２の例では、第１の方向Ｄ１も、磁化自由層２３とスペーサ層２２の界面に平行な方向である。第２の方向Ｄ２が第１の方向Ｄ１に対してなす角度θの範囲は、第１の実施の形態と同じである。第２の例では、磁化自由層２３とスペーサ層２２の界面に平行なＸＹ平面が、第１の実施の形態で定義した基準平面に該当する。 In the second example, the second direction D2 is a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 as in the first example, and coincides with the X direction. FIG. 10 shows a state in which the magnetization direction D3 of the magnetization free layer 23 coincides with the second direction D2 (X direction). In the second example, the first direction D <b> 1 is also a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22. The range of the angle θ formed by the second direction D2 with respect to the first direction D1 is the same as that in the first embodiment. In the second example, the XY plane parallel to the interface between the magnetization free layer 23 and the spacer layer 22 corresponds to the reference plane defined in the first embodiment.
　本実施の形態における磁化自由層２３は、磁化自由層２３とスペーサ層２２の界面に平行な方向に磁化容易軸を有することが好ましい。このような磁化自由層２３は、例えば、ＣｏＦｅ、ＣｏＦｅＢ、ＣｏＦｅＳｉ、ＣｏＭｎＧｅ、ＣｏＭｎＳｉ、ＣｏＭｎＡｌまたはホイスラー合金よりなる膜によって構成することができる。この膜の厚みは、１～１０ｎｍの範囲内であることが好ましい。 In the present embodiment, the magnetization free layer 23 preferably has an easy axis of magnetization in a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22. Such a magnetization free layer 23 can be constituted by a film made of, for example, CoFe, CoFeB, CoFeSi, CoMnGe, CoMnSi, CoMnAl, or Heusler alloy. The thickness of this film is preferably in the range of 1 to 10 nm.
　また、本実施の形態における磁化自由層２３は、複数の層によって構成されていてもよい。この場合、複数の層のうち、最もスペーサ層２２に近い層を、他の１つ以上の層よりもスピン分極率が高い高スピン分極率層とすることが好ましい。これにより、磁気抵抗効果素子２の抵抗変化率を大きくすることが可能になる。高スピン分極率層の材料としては、ＣｏＦｅ合金、ＣｏＦｅＢ合金等の高スピン分極率材料が用いられる。高スピン分極率層の厚みは、０．２～１．０ｎｍの範囲内であることが好ましい。 Further, the magnetization free layer 23 in the present embodiment may be composed of a plurality of layers. In this case, the layer closest to the spacer layer 22 among the plurality of layers is preferably a high spin polarizability layer having a higher spin polarizability than one or more other layers. As a result, the rate of change in resistance of the magnetoresistive effect element 2 can be increased. As a material of the high spin polarizability layer, a high spin polarizability material such as a CoFe alloy or a CoFeB alloy is used. The thickness of the high spin polarizability layer is preferably in the range of 0.2 to 1.0 nm.
　本実施の形態におけるその他の構成、作用および効果は、第１の実施の形態と同様である。 Other configurations, operations, and effects in the present embodiment are the same as those in the first embodiment.
［第３の実施の形態］
　次に、本発明の第３の実施の形態について説明する。始めに、図１１を参照して、本実施の形態に係る共振器１の構成について説明する。本実施の形態に係る共振器１の構成は、以下の点で第１の実施の形態と異なっている。本実施の形態に係る共振器１は、第１の実施の形態における外部磁界印加部３の代わりに、外部磁界印加部２０３を備えている。外部磁界印加部２０３は、磁気抵抗効果素子２の近傍に配置されている。 [Third Embodiment]
Next, a third embodiment of the present invention will be described. First, the configuration of the resonator 1 according to the present embodiment will be described with reference to FIG. The configuration of the resonator 1 according to the present embodiment is different from that of the first embodiment in the following points. The resonator 1 according to the present embodiment includes an external magnetic field application unit 203 instead of the external magnetic field application unit 3 in the first embodiment. The external magnetic field application unit 203 is disposed in the vicinity of the magnetoresistive element 2.
　外部磁界印加部２０３は、第１ないし第４の電磁石を含んでいる。具体的に説明すると、外部磁界印加部２０３は、それぞれ磁性材料よりなる第１のコア部２３３、第２のコア部２３４、第３のコア部２３５および第４のコア部２３６と、第１の導線２３１と、第２の導線２３２とを有している。第１の導線２３１は、第１のコア部２３３に巻回された第１の巻線部分と、第２のコア部２３４に巻回された第２の巻線部分とを含んでいる。第１の巻線部分と第２の巻線部分は、直列に接続されている。第１のコア部２３３と第１の巻線部分は、第１の電磁石を構成している。第２のコア部２３４と第２の巻線部分は、第２の電磁石を構成している。第２の導線２３２は、第３のコア部２３５に巻回された第３の巻線部分と、第４のコア部２３６に巻回された第４の巻線部分とを含んでいる。第３の巻線部分と第４の巻線部分は、直列に接続されている。第３のコア部２３５と第３の巻線部分は、第３の電磁石を構成している。第４のコア部２３６と第４の巻線部分は、第４の電磁石を構成している。 The external magnetic field application unit 203 includes first to fourth electromagnets. More specifically, the external magnetic field application unit 203 includes a first core unit 233, a second core unit 234, a third core unit 235, a fourth core unit 236, and a first core unit 233 each made of a magnetic material. It has a conducting wire 231 and a second conducting wire 232. The first conductive wire 231 includes a first winding part wound around the first core part 233 and a second winding part wound around the second core part 234. The first winding portion and the second winding portion are connected in series. The first core portion 233 and the first winding portion constitute a first electromagnet. The second core portion 234 and the second winding portion constitute a second electromagnet. The second conductive wire 232 includes a third winding portion wound around the third core portion 235 and a fourth winding portion wound around the fourth core portion 236. The third winding portion and the fourth winding portion are connected in series. The third core portion 235 and the third winding portion constitute a third electromagnet. The fourth core portion 236 and the fourth winding portion constitute a fourth electromagnet.
　第１および第２のコア部２３３，２３４は、磁気抵抗効果素子２の磁化自由層２３とスペーサ層２２の界面に垂直な方向における磁気抵抗効果素子２の両側に配置されている。第３および第４のコア部２３５，２３６は、磁気抵抗効果素子２の磁化自由層２３とスペーサ層２２の界面に平行な方向における磁気抵抗効果素子２の両側に配置されている。 The first and second core portions 233 and 234 are disposed on both sides of the magnetoresistive element 2 in the direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 of the magnetoresistive element 2. The third and fourth core portions 235 and 236 are disposed on both sides of the magnetoresistive element 2 in the direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 of the magnetoresistive element 2.
　外部磁界印加部２０３は、磁気抵抗効果素子２の磁化自由層２３に対して、第２の方向Ｄ２の外部磁界を印加する。磁化固定層２１は、少なくとも、第１の方向Ｄ１の磁化を有する第１の磁性層からなる。 The external magnetic field application unit 203 applies an external magnetic field in the second direction D2 to the magnetization free layer 23 of the magnetoresistive element 2. The magnetization fixed layer 21 includes at least a first magnetic layer having magnetization in the first direction D1.
　本実施の形態では、外部磁界印加部２０３は、外部磁界の大きさと、外部磁界の方向である第２の方向Ｄ２の両方を変化可能に構成されている。以下、これについて詳しく説明する。第１および第２の電磁石は、磁化自由層２３に対して、磁化自由層２３とスペーサ層２２の界面に垂直な方向の磁界を印加する。以下、この磁界を、外部磁界の垂直成分と言う。外部磁界の垂直成分の大きさは、第１の導線２３１に流される電流の大きさを調整することによって変化させることができる。また、外部磁界の垂直成分の方向は、第１の導線２３１に流される電流の方向を変えることによって、第１のコア部２３３から第２のコア部２３４に向かう方向とその反対方向との間で切り替えることができる。 In the present embodiment, the external magnetic field application unit 203 is configured to be able to change both the magnitude of the external magnetic field and the second direction D2, which is the direction of the external magnetic field. This will be described in detail below. The first and second electromagnets apply a magnetic field in a direction perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 to the magnetization free layer 23. Hereinafter, this magnetic field is referred to as a vertical component of the external magnetic field. The magnitude of the vertical component of the external magnetic field can be changed by adjusting the magnitude of the current flowing through the first conductor 231. The direction of the vertical component of the external magnetic field is changed between the direction from the first core part 233 toward the second core part 234 and the opposite direction by changing the direction of the current flowing through the first conductor 231. Can be switched.
　第３および第４の電磁石は、磁化自由層２３に対して、磁化自由層２３とスペーサ層２２の界面に平行な方向の磁界を印加する。以下、この磁界を、外部磁界の水平成分と言う。外部磁界の水平成分の大きさは、第２の導線２３２に流される電流の大きさを調整することによって変化させることができる。また、外部磁界の水平成分の方向は、第２の導線２３２に流される電流の方向を変えることによって、第３のコア部２３５から第４のコア部２３６に向かう方向とその反対方向との間で切り替えることができる。 The third and fourth electromagnets apply a magnetic field in a direction parallel to the interface between the magnetization free layer 23 and the spacer layer 22 to the magnetization free layer 23. Hereinafter, this magnetic field is referred to as a horizontal component of the external magnetic field. The magnitude of the horizontal component of the external magnetic field can be changed by adjusting the magnitude of the current flowing through the second conductor 232. The direction of the horizontal component of the external magnetic field is changed between the direction from the third core part 235 toward the fourth core part 236 and the opposite direction by changing the direction of the current flowing through the second conductor 232. Can be switched.
　磁化自由層２３に印加される外部磁界は、外部磁界の垂直成分と外部磁界の水平成分とが合成されたものである。そのため、本実施の形態では、外部磁界の垂直成分の大きさおよび方向と、外部磁界の水平成分の大きさおよび方向を変えることによって、外部磁界の大きさと第２の方向Ｄ２の両方を変えることができる。 The external magnetic field applied to the magnetization free layer 23 is a combination of the vertical component of the external magnetic field and the horizontal component of the external magnetic field. Therefore, in the present embodiment, both the magnitude of the external magnetic field and the second direction D2 are changed by changing the magnitude and direction of the vertical component of the external magnetic field and the magnitude and direction of the horizontal component of the external magnetic field. Can do.
　次に、図１２ないし図１４を参照して、本実施の形態における磁気抵抗効果素子２の構成の第１ないし第３の例と、本実施の形態における第１および第２の方向Ｄ１，Ｄ２の第１および第２の例について説明する。図１２ないし図１４には、第１の実施の形態における図２に示したＸ，Ｙ，Ｚの各方向も示している。図１２ないし図１４では、Ｙ方向を図１２ないし図１４における手前から奥に向かう方向としている。 Next, referring to FIGS. 12 to 14, first to third examples of the configuration of the magnetoresistive effect element 2 in the present embodiment, and the first and second directions D <b> 1 and D <b> 2 in the present embodiment. The first and second examples will be described. 12 to 14 also show the X, Y, and Z directions shown in FIG. 2 in the first embodiment. 12 to 14, the Y direction is a direction from the front to the back in FIGS. 12 to 14.
　図１２には、磁気抵抗効果素子２の構成の第１の例と、第１および第２の方向Ｄ１，Ｄ２の第１の例を示している。図１２に示した例では、磁化固定層２１は、第１の実施の形態と同様に、第１の方向Ｄ１の磁化を有する第１の磁性層のみからなる。また、図１２に示した例では、第１の方向Ｄ１は、磁化固定層２１とスペーサ層２２の界面に平行な方向であって、Ｘ方向とは反対の方向である。また、図１２に示した例では、第２の方向Ｄ２は、磁化自由層２３とスペーサ層２２の界面と交差する方向である。第２の方向Ｄ２が第１の方向Ｄ１に対してなす角度θの範囲は、第１の実施の形態と同じである。 FIG. 12 shows a first example of the configuration of the magnetoresistive effect element 2 and a first example of the first and second directions D1 and D2. In the example shown in FIG. 12, the magnetization fixed layer 21 is composed of only the first magnetic layer having the magnetization in the first direction D1, as in the first embodiment. In the example shown in FIG. 12, the first direction D1 is a direction parallel to the interface between the magnetization fixed layer 21 and the spacer layer 22 and is opposite to the X direction. In the example shown in FIG. 12, the second direction D <b> 2 is a direction that intersects the interface between the magnetization free layer 23 and the spacer layer 22. The range of the angle θ formed by the second direction D2 with respect to the first direction D1 is the same as that in the first embodiment.
　図１３には、磁気抵抗効果素子２の構成の第２の例を示している。図１３に示した例では、磁気抵抗効果素子２は、磁化固定層２１、磁化自由層２３およびスペーサ層２２に加えて、反強磁性層２４を含んでいる。反強磁性層２４は、磁化固定層２１におけるスペーサ層２２に接する面とは反対側の面に接するように設けられる。 FIG. 13 shows a second example of the configuration of the magnetoresistive effect element 2. In the example shown in FIG. 13, the magnetoresistive element 2 includes an antiferromagnetic layer 24 in addition to the magnetization fixed layer 21, the magnetization free layer 23, and the spacer layer 22. The antiferromagnetic layer 24 is provided so as to be in contact with the surface of the magnetization fixed layer 21 opposite to the surface in contact with the spacer layer 22.
　また、図１３に示した例では、磁化固定層２１は、第１の磁性層を含む複数の層からなる。具体的には、磁化固定層２１は、第１の磁性層２１１と、第２の磁性層２１２と、第１の磁性層２１１と第２の磁性層２１２の間に配置された非磁性層２１３とを含み、いわゆるシンセティック構造を有している。第１の磁性層２１１は、スペーサ層２２に接している。第２の磁性層２１２は、反強磁性層２４に接している。 In the example shown in FIG. 13, the magnetization fixed layer 21 is composed of a plurality of layers including the first magnetic layer. Specifically, the magnetization fixed layer 21 includes a first magnetic layer 211, a second magnetic layer 212, and a nonmagnetic layer 213 disposed between the first magnetic layer 211 and the second magnetic layer 212. And has a so-called synthetic structure. The first magnetic layer 211 is in contact with the spacer layer 22. The second magnetic layer 212 is in contact with the antiferromagnetic layer 24.
　第２の磁性層２１２は、反強磁性層２４との交換結合により、磁化の方向が実質的に固定されている。第１の磁性層２１１と第２の磁性層２１２は、反強磁性的に結合し、磁化の方向が互いに逆方向になっている。第１の磁性層２１１は、第１の方向Ｄ１の磁化を有している。図１３に示した第１の方向Ｄ１は、図１２に示した第１の方向Ｄ１と同じ方向であり、Ｘ方向とは反対の方向である。第２の磁性層２１２は、第１の方向Ｄ１とは反対方向の磁化を有している。図１３において、第２の磁性層２１２内に描かれた矢印は、第２の磁性層２１２の磁化の方向を表している。図１３に示した第２の磁性層２１２の磁化の方向は、Ｘ方向と一致する。 The magnetization direction of the second magnetic layer 212 is substantially fixed by exchange coupling with the antiferromagnetic layer 24. The first magnetic layer 211 and the second magnetic layer 212 are antiferromagnetically coupled and the magnetization directions are opposite to each other. The first magnetic layer 211 has magnetization in the first direction D1. The first direction D1 shown in FIG. 13 is the same direction as the first direction D1 shown in FIG. 12, and is the direction opposite to the X direction. The second magnetic layer 212 has magnetization in a direction opposite to the first direction D1. In FIG. 13, an arrow drawn in the second magnetic layer 212 represents the direction of magnetization of the second magnetic layer 212. The magnetization direction of the second magnetic layer 212 shown in FIG. 13 coincides with the X direction.
　第１および第２の磁性層２１１，２１２は、強磁性材料によって構成されている。第１および第２の磁性層２１１，２１２は、第１の実施の形態における磁化固定層２１を構成する強磁性材料と同じ材料によって構成されていてもよい。非磁性層２１３は、例えば、その全体がＲｕ等の非磁性の導電材料によって構成されている。 The first and second magnetic layers 211 and 212 are made of a ferromagnetic material. The first and second magnetic layers 211 and 212 may be made of the same material as the ferromagnetic material constituting the magnetization fixed layer 21 in the first embodiment. The nonmagnetic layer 213 is entirely made of, for example, a nonmagnetic conductive material such as Ru.
　図１４には、磁気抵抗効果素子２の構成の第３の例と、第１および第２の方向Ｄ１，Ｄ２の第２の例を示している。図１４に示した例では、磁気抵抗効果素子２の構成は、基本的には、図１３に示した例と同じである。ただし、図１４に示した例では、磁化固定層２１の第１および第２の磁性層２１１，２１２の磁化の方向が、図１３に示した方向と異なっている。図１４に示したように、第１の磁性層２１１の磁化の方向すなわち第１の方向Ｄ１は、磁化固定層２１とスペーサ層２２の界面に垂直な方向であって、Ｚ方向とは反対の方向である。第２の磁性層２１２の磁化の方向は、第１の方向Ｄ１とは反対の方向であり、Ｚ方向と一致する。図１４において、第２の磁性層２１２内に描かれた矢印は、第２の磁性層２１２の磁化の方向を表している。 FIG. 14 shows a third example of the configuration of the magnetoresistive effect element 2 and a second example of the first and second directions D1 and D2. In the example shown in FIG. 14, the configuration of the magnetoresistive effect element 2 is basically the same as the example shown in FIG. However, in the example shown in FIG. 14, the magnetization directions of the first and second magnetic layers 211 and 212 of the magnetization fixed layer 21 are different from those shown in FIG. 13. As shown in FIG. 14, the magnetization direction of the first magnetic layer 211, that is, the first direction D1, is a direction perpendicular to the interface between the magnetization fixed layer 21 and the spacer layer 22, and is opposite to the Z direction. Direction. The magnetization direction of the second magnetic layer 212 is opposite to the first direction D1 and coincides with the Z direction. In FIG. 14, an arrow drawn in the second magnetic layer 212 represents the direction of magnetization of the second magnetic layer 212.
　また、図１４に示した例では、第２の方向Ｄ２は、磁化自由層２３とスペーサ層２２の界面と交差する方向である。第２の方向Ｄ２が第１の方向Ｄ１に対してなす角度θの範囲は、第１の実施の形態と同じである。 In the example shown in FIG. 14, the second direction D2 is a direction intersecting the interface between the magnetization free layer 23 and the spacer layer 22. The range of the angle θ formed by the second direction D2 with respect to the first direction D1 is the same as that in the first embodiment.
　図１２ないし図１４に示した３つの例では、いずれも、少なくとも、磁化自由層２３とスペーサ層２２の界面に垂直なＸＺ平面が、第１の実施の形態で定義した基準平面に該当する。 In any of the three examples shown in FIGS. 12 to 14, at least the XZ plane perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22 corresponds to the reference plane defined in the first embodiment.
　本実施の形態に係る共振器１では、前述のように、外部磁界の大きさと第２の方向Ｄ２の両方を変えることができる。本実施の形態によれば、例えば、磁化自由層２３に強磁性共鳴を生じさせたときの磁化自由層２３の磁化の振動の中心軸を、磁化自由層２３とスペーサ層２２の界面に垂直な方向またはそれに近い方向に設定することが可能である。このように設定することにより、磁化自由層２３の磁化の方向によって磁化自由層２３の磁化に作用する異方性磁界が大きく異なることを防止することができる。これにより、高周波出力信号の波形の歪を抑制することができる。 In the resonator 1 according to the present embodiment, both the magnitude of the external magnetic field and the second direction D2 can be changed as described above. According to the present embodiment, for example, the central axis of magnetization vibration of the magnetization free layer 23 when ferromagnetic resonance is caused in the magnetization free layer 23 is perpendicular to the interface between the magnetization free layer 23 and the spacer layer 22. It is possible to set the direction or a direction close thereto. By setting in this way, it is possible to prevent the anisotropic magnetic field acting on the magnetization of the magnetization free layer 23 from greatly differing depending on the magnetization direction of the magnetization free layer 23. Thereby, distortion of the waveform of the high frequency output signal can be suppressed.
　本実施の形態におけるその他の構成、作用および効果は、第１の実施の形態と同様である。 Other configurations, operations, and effects in the present embodiment are the same as those in the first embodiment.
［第４の実施の形態］
　次に、本発明の第４の実施の形態について説明する。始めに、図１５を参照して、本実施の形態に係る共振器１の構成について説明する。本実施の形態に係る共振器１の構成は、以下の点で第３の実施の形態と異なっている。本実施の形態に係る共振器１は、第３の実施の形態におけるエネルギ付与部４の代わりに、エネルギ付与部１０４を備えている。 [Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. First, the configuration of the resonator 1 according to the present embodiment will be described with reference to FIG. The configuration of the resonator 1 according to the present embodiment is different from that of the third embodiment in the following points. The resonator 1 according to the present embodiment includes an energy applying unit 104 instead of the energy applying unit 4 in the third embodiment.
　エネルギ付与部１０４は、磁化自由層２３の磁化を振動させるためのエネルギとして、高周波磁界を、磁気抵抗効果素子２に付与するものである。エネルギ付与部１０４は、高周波磁界を発生するための１つ以上の電磁石を含んでいる。 The energy applying unit 104 applies a high frequency magnetic field to the magnetoresistive effect element 2 as energy for vibrating the magnetization of the magnetization free layer 23. The energy applying unit 104 includes one or more electromagnets for generating a high frequency magnetic field.
　本実施の形態では、第１のコア部２３３と第１の導線２３１の第１の巻線部分によって構成された第１の電磁石と、第２のコア部２３４と第１の導線２３１の第２の巻線部分によって構成された第２の電磁石が、高周波磁界を発生するための１つ以上の電磁石を兼ねている。以下、第１の導線２３１の両端を入力端２３１ａ，２３１ｂと言う。入力端２３１ａ，２３１ｂには、直流電流と、それに重畳された高周波電流が入力される。これにより、第１の導線２３１には、高周波電流が重畳された直流電流が流される。第１および第２の電磁石は、直流電流による外部磁界の垂直成分と、高周波電流による高周波磁界とを発生する。磁気抵抗効果素子２の磁化自由層２３には、第１および第２の電磁石によって発生された外部磁界の垂直成分および高周波磁界と、第３および第４の電磁石によって発生された外部磁界の水平成分とが合成された磁界が印加される。以下、この磁界を、高周波重畳磁界と言う。 In the present embodiment, the first electromagnet configured by the first core portion 233 and the first winding portion of the first conductor 231, the second core portion 234 and the second conductor 231 of the first conductor 231. The second electromagnet constituted by the winding portions also serves as one or more electromagnets for generating a high-frequency magnetic field. Hereinafter, both ends of the first conducting wire 231 are referred to as input ends 231a and 231b. A DC current and a high-frequency current superimposed thereon are input to the input terminals 231a and 231b. As a result, a direct current on which the high-frequency current is superimposed flows through the first conducting wire 231. The first and second electromagnets generate a vertical component of an external magnetic field caused by a direct current and a high frequency magnetic field caused by a high frequency current. The magnetization free layer 23 of the magnetoresistive effect element 2 has a vertical component and a high frequency magnetic field generated by the first and second electromagnets and a horizontal component of the external magnetic field generated by the third and fourth electromagnets. And a combined magnetic field is applied. Hereinafter, this magnetic field is referred to as a high frequency superimposed magnetic field.
　第３の実施の形態と同様に、外部磁界の方向は第２の方向Ｄ２である。高周波磁界は、高周波重畳磁界の方向を、第２の方向Ｄ２を中心として振動するように変化させる。高周波重畳磁界の方向の変化の周波数は、高周波電流の周波数と等しい。磁化自由層２３の磁化は、磁化自由層２３の磁化の方向Ｄ３が磁化固定層２１の磁化の方向Ｄ１に対してなす角度が変化するように、高周波電流の周波数で振動する。 As in the third embodiment, the direction of the external magnetic field is the second direction D2. The high-frequency magnetic field changes the direction of the high-frequency superimposed magnetic field so as to vibrate about the second direction D2. The frequency of change in the direction of the high-frequency superimposed magnetic field is equal to the frequency of the high-frequency current. The magnetization of the magnetization free layer 23 vibrates at the frequency of the high-frequency current so that the angle formed by the magnetization direction D3 of the magnetization free layer 23 with respect to the magnetization direction D1 of the magnetization fixed layer 21 changes.
　また、本実施の形態に係る共振器１は、第３の実施の形態における第１の信号線路６の代わりに、信号線路１０６を備えている。信号線路１０６の一端は、直流入力端子１５に電気的に接続されている。信号線路１０６の他端は、第１の電極１１に電気的に接続されている。本実施の形態に係る共振器１では、第３の実施の形態における入力ポート５は設けられていない。本実施の形態では、磁気抵抗効果素子２には、高周波電流が重畳されていない直流電流が流される。 In addition, the resonator 1 according to the present embodiment includes a signal line 106 instead of the first signal line 6 in the third embodiment. One end of the signal line 106 is electrically connected to the DC input terminal 15. The other end of the signal line 106 is electrically connected to the first electrode 11. In the resonator 1 according to the present embodiment, the input port 5 in the third embodiment is not provided. In the present embodiment, the magnetoresistive effect element 2 is supplied with a direct current on which no high-frequency current is superimposed.
　本実施の形態では、高周波磁界が磁気抵抗効果素子２に付与されると、磁化自由層２３の磁化に作用する有効磁界Ｈeffの方向が高周波電流の周波数で変化する。その結果、第１の実施の形態における式（１）を参照して説明したダンピングトルク（式（１）の第２項）が変化する。これにより、磁化自由層２３の磁化は、その方向が変化するように、高周波電流の周波数で振動する。その結果、高周波電流の周波数と等しい周波数の高周波出力信号が発生する。 In the present embodiment, when a high frequency magnetic field is applied to the magnetoresistive effect element 2, the direction of the effective magnetic field H eff acting on the magnetization of the magnetization free layer 23 changes with the frequency of the high frequency current. As a result, the damping torque described with reference to equation (1) in the first embodiment (the second term of equation (1)) changes. Thereby, the magnetization of the magnetization free layer 23 oscillates at the frequency of the high-frequency current so that its direction changes. As a result, a high frequency output signal having a frequency equal to the frequency of the high frequency current is generated.
　なお、上述のように有効磁界Ｈeffの方向が変化すると、第１の実施の形態における式（１）を参照して説明した歳差トルク（式（１）の第１項）も変化する。しかし、歳差トルクの変化が磁化自由層２３の磁化の振動に与える影響は、ダンピングトルクに比べて非常に小さい。 Note that when the direction of the effective magnetic field H eff changes as described above, the precession torque (the first term in the expression (1)) described with reference to the expression (1) in the first embodiment also changes. However, the influence of the change in precession torque on the vibration of magnetization of the magnetization free layer 23 is very small compared to the damping torque.
　高周波電流の周波数が磁化自由層２３の強磁性共鳴周波数と等しい場合には、磁化自由層２３において強磁性共鳴が生じて、磁化自由層２３の磁化の振動の振幅が最大になる。その結果、高周波出力信号の振幅も最大になる。 When the frequency of the high frequency current is equal to the ferromagnetic resonance frequency of the magnetization free layer 23, ferromagnetic resonance occurs in the magnetization free layer 23, and the amplitude of magnetization vibration of the magnetization free layer 23 is maximized. As a result, the amplitude of the high frequency output signal is also maximized.
　本実施の形態では、前述のように、磁気抵抗効果素子２には直流電流が供給される。従って、本実施の形態においても、第１の実施の形態と同様に、直流起因スピントランスファートルクが、磁化自由層２３の磁化に作用する。そのため、本実施の形態においても、第１の実施の形態と同様に、第２の方向Ｄ２が第１の方向Ｄ１に対してなす角度θは、９０°よりも大きいことが好ましく、９０°よりも大きく１５０°以下であることがより好ましく、１０５°～１３５°の範囲内であることがさらに好ましい。 In the present embodiment, as described above, a direct current is supplied to the magnetoresistive effect element 2. Therefore, also in the present embodiment, the direct current-induced spin transfer torque acts on the magnetization of the magnetization free layer 23 as in the first embodiment. Therefore, also in the present embodiment, as in the first embodiment, the angle θ formed by the second direction D2 with respect to the first direction D1 is preferably larger than 90 °, more than 90 °. Is more preferably 150 ° or less, and more preferably in the range of 105 ° to 135 °.
　なお、本実施の形態において、第１および第２の電磁石の代わりに、第３および第４の電磁石が、高周波磁界を発生するための１つ以上の電磁石を兼ねていてもよい。この場合には、第２の導線２３２には、高周波電流が重畳された直流電流が流される。そして、第３および第４の電磁石が、直流電流による外部磁界の水平成分と、高周波電流による高周波磁界とを発生する。 In the present embodiment, instead of the first and second electromagnets, the third and fourth electromagnets may also serve as one or more electromagnets for generating a high-frequency magnetic field. In this case, a direct current superimposed with a high-frequency current is passed through the second conducting wire 232. The third and fourth electromagnets generate a horizontal component of the external magnetic field due to the direct current and a high-frequency magnetic field due to the high-frequency current.
　本実施の形態におけるその他の構成、作用および効果は、第３の実施の形態と同様である。 Other configurations, operations, and effects in the present embodiment are the same as those in the third embodiment.
［第５の実施の形態］
　次に、本発明の第５の実施の形態について説明する。始めに、図１６を参照して、本実施の形態に係る共振器１の構成について説明する。本実施の形態に係る共振器１の構成は、以下の点で第３の実施の形態と異なっている。本実施の形態に係る共振器１は、第３の実施の形態におけるエネルギ付与部４の代わりに、エネルギ付与部２０４を備えている。 [Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. First, the configuration of the resonator 1 according to the present embodiment will be described with reference to FIG. The configuration of the resonator 1 according to the present embodiment is different from that of the third embodiment in the following points. The resonator 1 according to the present embodiment includes an energy applying unit 204 instead of the energy applying unit 4 in the third embodiment.
　エネルギ付与部２０４は、磁化自由層２３の磁化を振動させるためのエネルギとして、高周波磁界を、磁気抵抗効果素子２に付与するものである。エネルギ付与部２０４は、入力ポート５と、入力ポート５に印加された高周波入力信号に基づく高周波電流を伝送する高周波信号線路２０６を含んでいる。入力ポート５の構成は、第３の実施の形態と同じである。高周波信号線路２０６の一端は、入力ポート５の端子５１に電気的に接続されている。高周波信号線路２０６の他端は、グランド電極１３に電気的に接続されている。 The energy applying unit 204 applies a high-frequency magnetic field to the magnetoresistive effect element 2 as energy for vibrating the magnetization of the magnetization free layer 23. The energy applying unit 204 includes an input port 5 and a high-frequency signal line 206 that transmits a high-frequency current based on a high-frequency input signal applied to the input port 5. The configuration of the input port 5 is the same as that of the third embodiment. One end of the high-frequency signal transmission line 206 is electrically connected to the terminal 51 of the input port 5. The other end of the high-frequency signal transmission line 206 is electrically connected to the ground electrode 13.
　ここで、図１７を参照して、高周波信号線路２０６について詳しく説明する。図１７は、磁気抵抗効果素子２とその周辺を示す斜視図である。高周波信号線路２０６は、磁気抵抗効果素子２の近傍に配置された高周波磁界発生部２０６ａを含んでいる。高周波磁界発生部２０６ａは、Ｘ方向に平行な方向に細長い形状を有し、磁気抵抗効果素子２および第１の電極１１のＺ方向の先に配置されている。図１７では、高周波信号線路２０６のうち、高周波磁界発生部２０６ａとそれ以外の部分との境界を点線で示している。 Here, the high-frequency signal transmission line 206 will be described in detail with reference to FIG. FIG. 17 is a perspective view showing the magnetoresistive effect element 2 and its periphery. The high frequency signal line 206 includes a high frequency magnetic field generator 206 a disposed in the vicinity of the magnetoresistive element 2. The high-frequency magnetic field generation unit 206 a has a shape elongated in a direction parallel to the X direction, and is disposed ahead of the magnetoresistive effect element 2 and the first electrode 11 in the Z direction. In FIG. 17, in the high-frequency signal transmission line 206, the boundary between the high-frequency magnetic field generation unit 206a and the other part is indicated by a dotted line.
　高周波磁界発生部２０６ａは、高周波信号線路２０６を通過する高周波電流に基づいて高周波磁界を発生する。この高周波磁界の一部は、磁気抵抗効果素子２に付与される。磁気抵抗効果素子２に付与される高周波磁界の方向は、Ｙ方向に平行な方向である。 The high frequency magnetic field generation unit 206a generates a high frequency magnetic field based on a high frequency current passing through the high frequency signal line 206. A part of the high frequency magnetic field is applied to the magnetoresistive effect element 2. The direction of the high-frequency magnetic field applied to the magnetoresistive effect element 2 is a direction parallel to the Y direction.
　第３の実施の形態で説明したように、外部磁界印加部２０３は、第１ないし第４の電磁石を含み、磁気抵抗効果素子２の磁化自由層２３に対して、第２の方向Ｄ２の外部磁界を印加する。磁気抵抗効果素子２の磁化自由層２３には、第１および第２の電磁石によって発生された外部磁界の垂直成分と、第３および第４の電磁石によって発生された外部磁界の水平成分と、高周波磁界発生部２０６ａによって発生された高周波磁界が合成された磁界が印加される。以下、この磁界を、高周波重畳磁界と言う。 As described in the third embodiment, the external magnetic field application unit 203 includes first to fourth electromagnets, and is external to the magnetization free layer 23 of the magnetoresistive element 2 in the second direction D2. Apply a magnetic field. The magnetization free layer 23 of the magnetoresistive element 2 has a vertical component of the external magnetic field generated by the first and second electromagnets, a horizontal component of the external magnetic field generated by the third and fourth electromagnets, and a high frequency. A magnetic field obtained by synthesizing the high-frequency magnetic field generated by the magnetic field generation unit 206a is applied. Hereinafter, this magnetic field is referred to as a high frequency superimposed magnetic field.
　第３の実施の形態と同様に、外部磁界の方向は第２の方向Ｄ２である。高周波磁界は、高周波重畳磁界の方向を、第２の方向Ｄ２を中心としてＹ方向に平行な方向に振動するように変化させる。高周波重畳磁界の方向の変化の周波数は、高周波電流の周波数と等しい。磁化自由層２３の磁化は、磁化自由層２３の磁化の方向Ｄ３が磁化固定層２１の磁化の方向Ｄ１に対してなす角度が変化するように、高周波電流の周波数で振動する。 As in the third embodiment, the direction of the external magnetic field is the second direction D2. The high-frequency magnetic field changes the direction of the high-frequency superimposed magnetic field so as to vibrate in a direction parallel to the Y direction with the second direction D2 as the center. The frequency of change in the direction of the high-frequency superimposed magnetic field is equal to the frequency of the high-frequency current. The magnetization of the magnetization free layer 23 vibrates at the frequency of the high-frequency current so that the angle formed by the magnetization direction D3 of the magnetization free layer 23 with respect to the magnetization direction D1 of the magnetization fixed layer 21 changes.
　また、本実施の形態に係る共振器１は、更に、信号線路１７と直流入力端子１８とを備えている。信号線路１７の一端は、第１の電極１１に電気的に接続されている。信号線路１７の他端は、グランド電極１３に電気的に接続されている。直流入力端子１８は、チョークコイル１４とグランド電極１３との間に設けられている。なお、本実施の形態では、第３の実施の形態における直流入力端子１５は設けられていない。 The resonator 1 according to the present embodiment further includes a signal line 17 and a DC input terminal 18. One end of the signal line 17 is electrically connected to the first electrode 11. The other end of the signal line 17 is electrically connected to the ground electrode 13. The DC input terminal 18 is provided between the choke coil 14 and the ground electrode 13. In the present embodiment, the DC input terminal 15 in the third embodiment is not provided.
　本実施の形態では、共振器１を動作させる際には、図１６に示したように、直流入力端子１８とグランド電極１３の間に直流電流源１６が設けられる。これにより、信号線路１７、磁気抵抗効果素子２、第２の信号線路７、チョークコイル１４、直流入力端子１８、直流電流源１６およびグランド電極１３を含む閉回路が形成される。直流電流源１６は、この閉回路を流れる直流電流を発生する。磁気抵抗効果素子２では、磁化自由層２３から磁化固定層２１に向かう方向に直流電流が流れる。本実施の形態では特に、磁気抵抗効果素子２には、高周波電流が重畳されていない直流電流が流される。 In this embodiment, when the resonator 1 is operated, the DC current source 16 is provided between the DC input terminal 18 and the ground electrode 13 as shown in FIG. As a result, a closed circuit including the signal line 17, the magnetoresistive effect element 2, the second signal line 7, the choke coil 14, the DC input terminal 18, the DC current source 16, and the ground electrode 13 is formed. The direct current source 16 generates a direct current flowing through this closed circuit. In the magnetoresistive effect element 2, a direct current flows in a direction from the magnetization free layer 23 toward the magnetization fixed layer 21. Particularly in the present embodiment, a direct current on which a high-frequency current is not superimposed is passed through the magnetoresistive effect element 2.
　本実施の形態では、第４の実施の形態と同様に、磁気抵抗効果素子２に印加される高周波磁界による磁化自由層２３の磁化の振動に起因する高周波出力信号が発生する。本実施の形態におけるその他の構成、作用および効果は、第３または第４の実施の形態と同様である。 In the present embodiment, as in the fourth embodiment, a high frequency output signal is generated due to the vibration of magnetization of the magnetization free layer 23 caused by the high frequency magnetic field applied to the magnetoresistive effect element 2. Other configurations, operations, and effects in the present embodiment are the same as those in the third or fourth embodiment.
［第６の実施の形態］
　次に、本発明の第６の実施の形態について説明する。始めに、図１８を参照して、本実施の形態に係る共振器１の構成について説明する。本実施の形態に係る共振器１の構成は、以下の点で第３の実施の形態と異なっている。本実施の形態に係る共振器１は、直流入力端子１８と、信号線路１９とを備えている。直流入力端子１８は、チョークコイル１４とグランド電極１３との間に設けられている。信号線路１９の一端は、第１の電極１１に電気的に接続されている。信号線路１９の他端は、グランド電極１３に電気的に接続されている。なお、本実施の形態では、第３の実施の形態における直流入力端子１５は設けられていない。 [Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. First, the configuration of the resonator 1 according to the present embodiment will be described with reference to FIG. The configuration of the resonator 1 according to the present embodiment is different from that of the third embodiment in the following points. The resonator 1 according to the present embodiment includes a DC input terminal 18 and a signal line 19. The DC input terminal 18 is provided between the choke coil 14 and the ground electrode 13. One end of the signal line 19 is electrically connected to the first electrode 11. The other end of the signal line 19 is electrically connected to the ground electrode 13. In the present embodiment, the DC input terminal 15 in the third embodiment is not provided.
　ここで、図１９を参照して、本実施の形態における第１の電極１１の形状について説明する。図１９は、磁気抵抗効果素子２とその周辺を示す斜視図である。本実施の形態では、第１の電極１１は、Ｘ方向に平行な方向に細長い形状を有している。第１の電極１１は、Ｘ方向の先に位置する第１の端部と、その反対側の第２の端部とを有している。図１９に示した例では、第１の端部に信号線路１９が接続され、第２の端部に第１の信号線路６が接続されている。図１９では、第１の電極１１と第１の信号線路６との境界および第１の電極１１と信号線路１９との境界を点線で示している。なお、図１９に示した例とは逆に、第１の端部に第１の信号線路６が接続され、第２の端部に信号線路１９が接続されていてもよい。 Here, the shape of the first electrode 11 in the present embodiment will be described with reference to FIG. FIG. 19 is a perspective view showing the magnetoresistive effect element 2 and its periphery. In the present embodiment, the first electrode 11 has an elongated shape in a direction parallel to the X direction. The first electrode 11 has a first end located at the tip of the X direction and a second end opposite to the first end. In the example shown in FIG. 19, the signal line 19 is connected to the first end, and the first signal line 6 is connected to the second end. In FIG. 19, the boundary between the first electrode 11 and the first signal line 6 and the boundary between the first electrode 11 and the signal line 19 are indicated by dotted lines. In contrast to the example shown in FIG. 19, the first signal line 6 may be connected to the first end, and the signal line 19 may be connected to the second end.
　本実施の形態では、共振器１を動作させる際には、図１８に示したように、直流入力端子１８とグランド電極１３の間に直流電流源１６が設けられる。これにより、信号線路１９、磁気抵抗効果素子２、第２の信号線路７、チョークコイル１４、直流入力端子１８、直流電流源１６およびグランド電極１３を含む閉回路が形成される。直流電流源１６は、この閉回路を流れる直流電流を発生する。磁気抵抗効果素子２では、磁化自由層２３から磁化固定層２１に向かう方向に直流電流が流れる。 In this embodiment, when the resonator 1 is operated, a direct current source 16 is provided between the direct current input terminal 18 and the ground electrode 13 as shown in FIG. As a result, a closed circuit including the signal line 19, the magnetoresistive effect element 2, the second signal line 7, the choke coil 14, the DC input terminal 18, the DC current source 16, and the ground electrode 13 is formed. The direct current source 16 generates a direct current flowing through this closed circuit. In the magnetoresistive effect element 2, a direct current flows in a direction from the magnetization free layer 23 toward the magnetization fixed layer 21.
　本実施の形態におけるエネルギ付与部４は、磁化自由層２３の磁化を振動させるためのエネルギとして、高周波磁界と高周波電流を、磁気抵抗効果素子２に付与するものである。本実施の形態では、入力ポート５に印加された高周波入力信号に基づく高周波電流は、第１の信号線路６、第１の電極１１および信号線路１９を通過する。第１の電極１１は、第１の電極１１を通過する高周波電流に基づいて高周波磁界を発生する。この高周波磁界の一部は、磁気抵抗効果素子２に付与される。磁気抵抗効果素子２に付与される高周波磁界の方向は、図１９に示したＹ方向に平行な方向である。また、第１の電極１１に供給された高周波電流の一部は、磁気抵抗効果素子２を流れる直流電流に重畳されて、磁気抵抗効果素子２に付与される。 The energy applying unit 4 in the present embodiment applies a high-frequency magnetic field and a high-frequency current to the magnetoresistive effect element 2 as energy for vibrating the magnetization of the magnetization free layer 23. In the present embodiment, a high frequency current based on a high frequency input signal applied to the input port 5 passes through the first signal line 6, the first electrode 11, and the signal line 19. The first electrode 11 generates a high frequency magnetic field based on the high frequency current passing through the first electrode 11. A part of the high frequency magnetic field is applied to the magnetoresistive effect element 2. The direction of the high-frequency magnetic field applied to the magnetoresistive effect element 2 is a direction parallel to the Y direction shown in FIG. A part of the high-frequency current supplied to the first electrode 11 is superimposed on the direct current flowing through the magnetoresistive effect element 2 and applied to the magnetoresistive effect element 2.
　本実施の形態では、磁気抵抗効果素子２に印加される高周波磁界による磁化自由層２３の磁化の振動と磁気抵抗効果素子２を流れる高周波電流による磁化自由層２３の磁化の振動とに起因する高周波出力信号が発生する。本実施の形態におけるその他の構成、作用および効果は、第３または第５の実施の形態と同様である。 In the present embodiment, the high frequency caused by the vibration of magnetization of the magnetization free layer 23 caused by the high frequency magnetic field applied to the magnetoresistive effect element 2 and the vibration of magnetization of the magnetization free layer 23 caused by the high frequency current flowing through the magnetoresistive effect element 2. An output signal is generated. Other configurations, operations, and effects in the present embodiment are the same as those in the third or fifth embodiment.
　なお、本発明は、上記各実施の形態に限定されず、種々の変更が可能である。例えば、本発明における外部磁界印加部は、１つ以上の電磁石の代わりに、磁化自由層２３の近くに配置された１つ以上の導線を含んでいてもよい。この１つ以上の導線は、通電されることによって、その周りに磁界を発生する。この磁界の一部が外部磁界となる。 The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the external magnetic field application unit in the present invention may include one or more conductors arranged near the magnetization free layer 23 instead of one or more electromagnets. The one or more conductors generate a magnetic field around them when energized. A part of this magnetic field becomes an external magnetic field.
　また、本発明における外部磁界印加部は、１つ以上の電磁石の代わりに、１つ以上の永久磁石を含んでいてもよい。第３の実施の形態では、第１および第２の電磁石の代わりに、外部磁界の垂直成分を発生する１つ以上の永久磁石を設けてもよい。この場合には、第３および第４の電磁石を用いて、外部磁界の水平成分の大きさと方向の少なくとも一方を変えることによって、外部磁界の方向である第２の方向Ｄ２を変化させることが可能である。あるいは、第３の実施の形態において、第３および第４の電磁石の代わりに、外部磁界の水平成分を発生する１つ以上の永久磁石を設けてもよい。この場合には、第１および第２の電磁石を用いて、外部磁界の垂直成分の大きさと方向の少なくとも一方を変えることによって、外部磁界の方向である第２の方向Ｄ２を変化させることが可能である。 In addition, the external magnetic field application unit in the present invention may include one or more permanent magnets instead of one or more electromagnets. In the third embodiment, one or more permanent magnets that generate a vertical component of the external magnetic field may be provided instead of the first and second electromagnets. In this case, the second direction D2, which is the direction of the external magnetic field, can be changed by using the third and fourth electromagnets to change at least one of the magnitude and direction of the horizontal component of the external magnetic field. It is. Alternatively, in the third embodiment, one or more permanent magnets that generate a horizontal component of the external magnetic field may be provided instead of the third and fourth electromagnets. In this case, the second direction D2, which is the direction of the external magnetic field, can be changed by changing at least one of the magnitude and direction of the vertical component of the external magnetic field using the first and second electromagnets. It is.

Claims (12)

  1. 　少なくとも第１の磁性層からなる磁化固定層と、方向が変化する磁化を有する磁化自由層と、前記磁化固定層と磁化自由層の間に配置され且つ前記第１の磁性層に接するスペーサ層とを含む磁気抵抗効果素子であって、前記第１の磁性層は第１の方向の磁化を有するものである磁気抵抗効果素子と、
    　前記磁気抵抗効果素子の前記磁化自由層に対して、第２の方向の静磁界である外部磁界を印加する外部磁界印加部と、
    　前記磁化自由層の磁化を振動させるためのエネルギを前記磁気抵抗効果素子に付与するエネルギ付与部とを備えた共振器であって、
    　前記第２の方向が前記第１の方向に対してなす角度は、９０°～１５０°の範囲内であることを特徴とする共振器。     A magnetization fixed layer comprising at least a first magnetic layer; a magnetization free layer having a magnetization whose direction changes; a spacer layer disposed between the magnetization fixed layer and the magnetization free layer and in contact with the first magnetic layer; A magnetoresistive element including the first magnetic layer having magnetization in a first direction; and
    An external magnetic field application unit that applies an external magnetic field that is a static magnetic field in a second direction to the magnetization free layer of the magnetoresistive element;
    A resonator including an energy applying unit that applies energy for vibrating the magnetization of the magnetization free layer to the magnetoresistive element;
    An angle formed by the second direction with respect to the first direction is in a range of 90 ° to 150 °.
  2. 　前記エネルギ付与部は、高周波電流を、前記エネルギとして前記磁気抵抗効果素子に付与することを特徴とする請求項１記載の共振器。 2. The resonator according to claim 1, wherein the energy applying unit applies a high-frequency current to the magnetoresistive effect element as the energy.
  3. 　前記エネルギ付与部は、高周波磁界を、前記エネルギとして前記磁気抵抗効果素子に付与することを特徴とする請求項１記載の共振器。 2. The resonator according to claim 1, wherein the energy applying unit applies a high-frequency magnetic field to the magnetoresistive effect element as the energy.
  4. 　前記第２の方向が前記第１の方向に対してなす角度は、１０５°～１３５°の範囲内であることを特徴とする請求項１ないし３のいずれかに記載の共振器。 4. The resonator according to claim 1, wherein an angle formed by the second direction with respect to the first direction is in a range of 105 ° to 135 °.
  5. 　前記第１の方向と前記第２の方向の少なくとも一方は、前記磁化自由層と前記スペーサ層の界面と交差する方向であることを特徴とする請求項１ないし４のいずれかに記載の共振器。 5. The resonator according to claim 1, wherein at least one of the first direction and the second direction is a direction intersecting an interface between the magnetization free layer and the spacer layer. 6. .
  6. 　前記第２の方向は、前記磁化自由層と前記スペーサ層の界面に垂直な方向であることを特徴とする請求項１ないし４のいずれかに記載の共振器。 5. The resonator according to claim 1, wherein the second direction is a direction perpendicular to an interface between the magnetization free layer and the spacer layer.
  7. 　前記第２の方向は、前記磁化自由層と前記スペーサ層の界面に平行な方向であることを特徴とする請求項１ないし４のいずれかに記載の共振器。 5. The resonator according to claim 1, wherein the second direction is a direction parallel to an interface between the magnetization free layer and the spacer layer.
  8. 　前記第１の方向は、前記磁化固定層と前記スペーサ層の界面に垂直な方向であることを特徴とする請求項１ないし４のいずれかに記載の共振器。 The resonator according to any one of claims 1 to 4, wherein the first direction is a direction perpendicular to an interface between the fixed magnetization layer and the spacer layer.
  9. 　前記第１の方向は、前記磁化固定層と前記スペーサ層の界面に平行な方向であることを特徴とする請求項１ないし４のいずれかに記載の共振器。 The resonator according to any one of claims 1 to 4, wherein the first direction is a direction parallel to an interface between the magnetization fixed layer and the spacer layer.
  10. 　前記外部磁界印加部は、前記外部磁界の大きさを変化可能であることを特徴とする請求項１ないし９のいずれかに記載の共振器。 10. The resonator according to claim 1, wherein the external magnetic field application unit is capable of changing the magnitude of the external magnetic field.
  11. 　前記外部磁界印加部は、前記第２の方向を変化可能であることを特徴とする請求項１ないし１０のいずれかに記載の共振器。 The resonator according to any one of claims 1 to 10, wherein the external magnetic field application unit is capable of changing the second direction.
  12. 　更に、前記磁化自由層の磁化の振動に起因する高周波出力信号が現れる出力ポートを備えたことを特徴とする請求項１ないし１１のいずれかに記載の共振器。 The resonator according to claim 1, further comprising an output port through which a high-frequency output signal resulting from vibration of magnetization of the magnetization free layer appears.
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