JP5238783B2 - Oscillating element - Google Patents

Description

  Embodiments described herein relate generally to a high-frequency oscillation element, and more particularly, to a small high-frequency oscillation element that generates a terahertz wave.

  "Terahertz wave" is a kind of infrared in a broad sense, but it is a wave whose frequency is between electromagnetic waves and light. In this specification, the frequency ranges from 0.1 THz to 100 THz.

  Various excitations of solids and gases (phonons, plasmons, superconducting energy gaps, intermolecular vibrations, etc.) exist in the terahertz frequency region. For this reason, when various materials are irradiated with terahertz waves, interactions such as absorption and reflection occur, and analysis and inspection of various materials using this are expected.

  Conventional terahertz wave generation technology uses a femtosecond laser. However, especially when used for a large number of specimens in medical diagnosis / testing and environmental measurement, a small and inexpensive device is required. It has not spread as a source.

  Furthermore, in the atmosphere, terahertz waves are largely attenuated due to absorption by water vapor, and the propagation distance is limited. Therefore, it is highly effective to downsize the entire transmitting element-analyte-receiving element. It is necessary to downsize each of the transmitting element and the receiving element.

On the other hand, a spin torque oscillator (STO: Spin Torque Oscillator) that oscillates a high frequency in the GHz band by precessing the magnetization in a magnetic material has been proposed as a small element capable of high-frequency transmission (non-patent document). 1) The experiment was verified (Non-patent Document 2). STO is a phenomenon in which, when a spin current is passed through a ferromagnet, the magnetization of the ferromagnet interacts with the spin of the current and precesses. The frequency of precession becomes the oscillation frequency. This phenomenon requires the current density of the spin current to be as high as about 1 × 10 ⁸ A / cm2, so it can be expressed by flowing current through a fine element, which makes it a terahertz wave oscillator that requires miniaturization. It is a suitable phenomenon. The oscillation frequency is still as low as several GHz to several tens of GHz. However, when the optical mode is used compared to the acoustic mode that is usually observed, an oscillation frequency several times or more can be obtained. In order to realize the optical mode, it is theoretically suggested and proposed that a laminated film in which two magnetic layers are magnetically coupled in antiparallel is suitable (Non-patent Document 3).

J. C. Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996). S. I. Kiselev et al, Nature 425, 308 (2003). T. Seki et.al., Appl.Phys.Lett., 94, 212605 (2009).

  However, even a laminated film using antiparallel coupling has a theoretical prediction that the oscillation frequency is as low as several tens of GHz and has not yet achieved a terahertz wave frequency.

An oscillation element according to an aspect of the present invention includes a first magnetic layer whose magnetization is fixed in one direction, a second magnetic layer having a first magnetic domain and a second magnetic domain, and the first magnetic layer And a coupling intermediate layer inserted between the second magnetic layer and an electrode for passing an electric current to the laminated film perpendicularly to the film surface of the laminated film. When the laminated film is not energized , the relative angle between the magnetization of the first magnetic layer and the magnetization of the first magnetic domain is + 90 °, and the magnetization of the first magnetic layer and the second magnetic domain are The relative angle to the magnetization of −90 ° is −90 °, and in the state where the laminated film is energized, the magnetization of the second magnetic layer oscillates to oscillate electromagnetic waves or light.

It is a sketch showing a first embodiment of the present invention. It is a figure which shows MR curve and magnetization curve in 1st embodiment of this invention. It is a figure which shows the oscillation state of 1st embodiment of this invention. It is a sketch which shows the comparative example of 1st embodiment of this invention. It is a figure which shows the oscillation state of the comparative example of 1st embodiment of this invention. It is a sketch which shows 2nd embodiment of this invention. It is a figure which shows the oscillation state of 2nd embodiment of this invention. It is a sketch which shows 3rd embodiment of this invention. It is a figure which shows the oscillation state of 3rd embodiment of this invention. It is a sketch which shows 4th embodiment of this invention. It is a sketch showing a fifth embodiment of the present invention. It is a sketch showing a sixth embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. Those denoted by the same reference numerals indicate similar configurations. 1 and the like are schematic or conceptual diagrams, and the relationship between the thickness and width of each part, the ratio coefficient of the size between the parts, and the like are not necessarily the same as those of an actual element. Further, even when the same part is represented, the dimensions and ratio coefficient may be represented differently depending on the drawing.

(First embodiment)
FIG. 1 is a sketch of the oscillation element according to the first embodiment. First, the configuration of the oscillation element will be described with reference to the drawings.

  The oscillation element of the present embodiment includes a first magnetic layer 10, a coupling intermediate layer 11 provided on the first magnetic layer 10, and a second magnetic layer 12 provided on the coupling intermediate layer 11. ing. An upper electrode 14 and a lower electrode 13 are formed so as to sandwich a laminated film composed of the first magnetic layer 10, the coupling intermediate layer 11, and the second magnetic layer 12. The upper electrode 14 and the lower electrode 13 are configured to pass a current perpendicular to the film surface of the laminated film.

  When the first magnetic layer 10 and the second magnetic layer 12 are not energized, their magnetizations are magnetically coupled to each other at a relative angle of +90 degrees via the coupling intermediate layer 11, and magnetically coupled to -90 degrees. A plurality of parts. In this example, as shown in FIG. 1, the second magnetic layer 12 is separated into a plurality of magnetic domains, and each is magnetically coupled at +90 degrees and −90 degrees with respect to the magnetization of the first magnetic layer 10. It is a configuration.

  For the first magnetic layer 10 and the second magnetic layer 12, a ferromagnetic material, for example, an alloy containing a 3d transition metal such as Fe, Co, or Ni can be used. Furthermore, an alloy obtained by adding an additive element such as Cu, Al, Mg, Pd, Pt, or Ru can be used.

  The coupling intermediate layer 11 has an action of coupling the magnetization of the first magnetic layer 10 and the magnetization of the second magnetic layer 12 orthogonally. As a material of the bonding intermediate layer 11, a layer containing an oxide obtained by oxidizing Fe, Co, Ni, Cr, Mn, Zn, or an alloy containing any of these can be used.

  Next, the operation principle will be described.

  In the oscillation element of this embodiment, when the state of magnetic coupling between the first magnetic layer 10 and the second magnetic layer 12 in a state where no current is applied is 90 ° coupling, spin torque oscillation (STO) It is characterized in that a high oscillation frequency can be obtained when energizing to a current density that develops. Therefore, the 90 ° coupling in the non-energized state and the STO in the energized state will be sequentially described.

  First, regarding 90 ° coupling, in general, the magnetic coupling of the ferromagnetic layer / coupled intermediate layer / ferromagnetic layer structure is based on periodic coupling of ferromagnetic coupling and antiferromagnetic coupling to the thickness of the coupling intermediate layer. Shows oscillating RKKY interaction. On the other hand, depending on the material of the coupling intermediate layer, a 90 ° coupling which is neither a ferromagnetic coupling nor an antiferromagnetic coupling may be exhibited. In the old days, it was observed in the Fe / Cr / Fe trilayer structure, and then 90 ° bond was also reported in the CoFe / Mn / CoFe trilayer structure. However, since the energy of these 90 ° bonds is very small, it is difficult to obtain a stable state and it is not suitable for device application. On the other hand, using a bonded intermediate layer containing an oxide obtained by oxidizing Fe, Co, Ni, Cr, Mn, Zn, or an alloy containing any of these, is stronger than conventional bonded intermediate layers of metals. It was found that a stable 90 ° bond was obtained.

で表される。ここでA₁₂は通常の双一次交換結合定数、B₁₂は双二次交換結合定数である。第１項は２層の強磁性層の磁化が相対的に平行あるいは反平行のときに最小となり、A₁₂＜０のとき反平行、A₁₂＞０のとき平行となる。第2項は2層の強磁性層の磁化のなす角が0°（平行）、90°、180°（反平行）、270°のいずれかの場合に最小となる。B₁₂＜０では90°、270°、B₁₂＞０では0°、180°となる。ここで、90°と270°のとるエネルギーは縮退しているので、以下では90°あるいは270°の相対角度をとる結合を90°結合と呼ぶ。90°結合は、第１項よりも第２項の寄与が大きく、第２項のエネルギーが90°あるいは270°で最小となる条件、すなわち、｜A₁₂｜＜｜B₁₂｜かつB₁₂＜０のときに生じる。｜A₁₂｜＜｜B₁₂｜という条件は、A₁₂＜０（反平行）とA₁₂＞０（平行）の状態が混在し、競合する場合に誘起される。そして、｜B₁₂｜が大きいほど90°結合は安定となる。 The case where the 90 ° coupling is greatly expressed will be described using the energy of coupling of the ferromagnetic layer through the layer inserted between the two ferromagnetic layers. Magnetic coupling energy E _ex is

It is represented by Here, A ₁₂ is a normal bilinear exchange coupling constant, and B ₁₂ is a biquadratic exchange coupling constant. The first term is minimized when the magnetizations of the two ferromagnetic layers are relatively parallel or antiparallel, antiparallel when A ₁₂ <0, and parallel when A ₁₂ > 0. The second term is minimized when the angle between the magnetizations of the two ferromagnetic layers is 0 ° (parallel), 90 °, 180 ° (antiparallel), or 270 °. When B ₁₂ <0, the angle is 90 ° and 270 °, and when B ₁₂ > 0, the angle is 0 ° and 180 °. Here, since the energy taken by 90 ° and 270 ° is degenerated, a bond taking a relative angle of 90 ° or 270 ° is hereinafter referred to as a 90 ° bond. In the 90 ° coupling, the contribution of the second term is larger than that of the first term, and the condition that the energy of the second term is minimum at 90 ° or 270 °, that is, | A ₁₂ | <| B ₁₂ | and B ₁₂ < Occurs when zero. The condition of | A ₁₂ | <| B ₁₂ | is induced when the states of A ₁₂ <0 (antiparallel) and A ₁₂ > 0 (parallel) are mixed and conflicting. The larger the | B ₁₂ |, the more stable the 90 ° coupling.

Here, for obtaining the biquadratic exchange coupling constant B ₁₂ binding intermediate layer containing an oxide of Fe, a model membrane created. The film structure is: underlayer / antiferromagnetic layer IrMn (7 nm) / first magnetic layer Fe ₁₀ Co ₉₀ (2 nm) / coupled intermediate layer / second magnetic layer Fe ₁₀ Co ₉₀ (2 nm) / Cu ( 3 nm) / Fe ₁₀ Co ₉₀ (2 nm) / protective layer. In the bonding interlayer, Fe (2 nm) was naturally oxidized with an oxygen exposure of 3 kilolangmuir (kL). In order to obtain the biquadratic exchange coupling constant B ₁₂ from the magnetic field H ₉₀ where the 90 ° coupling is broken, it is necessary to fix the magnetization of the first or second magnetic layer. Here, the magnetization of the first magnetic layer is fixed in one direction by the antiferromagnetic layer IrMn. FIG. 2A shows the magnetization curve, and FIG. 2B shows the MR curve. The angle between the fixing direction by IrMn and the magnetic field of insertion is ± 90 °. From FIG. 2, the magnetic field H ₉₀ tear of 90 ° binding was found to 450 Oe. The magnetization curve and MR curve were symmetric with respect to the sign of the magnetic field that was inserted. This is because of the magnitude of the magnetic field that breaks the 90 ° coupling when the magnetic field is applied at + 90 ° to the fixing direction and the insertion magnetic field by IrMn, and the magnetic field that breaks the 270 ° coupling when the magnetic field is applied at -90 °. Indicates that they are the same size. From this, it is clear that 90 ° bond and 270 ° bond occur with the same energy. Here, it means that a region magnetically coupled at + 90 ° and a region magnetically coupled at + 270 ° exist. Since + 270 ° is equivalent to −90 °, it can be said that the magnetic coupling is ± 90 °.

Fe₁₀Co₉₀の飽和磁化M_sは約1.8 Tであり、結合中間層において全てのFe層が酸化されて磁気モーメントを失うと仮定してこれらの値を（２）式に代入すると、B₁₂は-0.26 mJ/m²と求めることが出来た。この絶対値は、結合中間層が非磁性体のAu、Al、Ag、Cuの場合には、双二次交換結合定数B₁₂の絶対値が0.003〜0.1 erg/cm²に比べ、非常に大きい。 Estimate the biquadratic exchange coupling constant B _12. B ₁₂ when the 90 ° coupling of the two ferromagnetic layers having the saturation magnetization M _s and the film thicknesses t ₁ and t ₂ is broken by the magnetic field H ₉₀ is expressed as follows.

Saturation magnetization M _s of Fe ₁₀ Co ₉₀ is approximately 1.8 T, when all the Fe layer in the bonded intermediate layer Substituting these values into equation (2) assuming it is oxidized loses magnetic moment, B ₁₂ was able to obtain a -0.26 mJ / m ^2. The absolute value, Au bond intermediate layer is a non-magnetic material, Al, Ag, in the case of Cu, the absolute value of the biquadratic exchange coupling constant B ₁₂ is compared to the 0.003 to 0.1 erg / cm ^2, a very large .

Similarly, Co, Ni, FeCo alloy, NiFe alloy were determined CoNi alloys, FeCoNi alloy, Cr, Mn, the biquadratic exchange coupling constant B ₁₂ binding intermediate layer produced by oxidizing the Zn, the absolute All values were 0.2 erg / cm ² or more.

  Next, the energized STO will be described.

The STO is an electron that bears a current when a current greater than a threshold value flows from the second magnetic layer 12 in the stacking direction of the stacked film composed of the first magnetic layer 10 / the coupling intermediate layer 11 / the second magnetic layer 12. Reaches the second magnetic layer 12 with a spin reflecting the magnetization state of the first magnetic layer 10, the magnetization of the second magnetic layer 12 receives a rotational torque due to the interaction, and precesses. This is a phenomenon of high-frequency oscillation. The threshold current is generally about 10 ⁸ A / cm ² below which STO does not develop. Therefore, the magnetization state when a current equal to or less than the threshold value is passed is the same as the state where no current is applied. In the present invention, “a state where current is not applied” is used to mean “a state where current exceeding the threshold is not passed”.

  In order to increase this oscillation frequency, STO using optical mode oscillation has been proposed. The oscillation frequency is several times higher than the STO Acoustic mode that is usually observed. Optical mode oscillation is predicted from theoretical calculations to be obtained when the first magnetic layer 10 and the second magnetic layer 12 are magnetically coupled in antiparallel, and experiments have been conducted. From this theoretical prediction, in the laminated film in which the two layers of magnetic materials are 90 ° magnetically coupled, we noticed the possibility that the magnetization of the second magnetic layer 12 oscillates at a higher oscillation frequency and oscillates electromagnetic waves or light when energized. The present invention has been reached.

ｊは磁性層の番号、tは磁性層の膜厚である。ここで、磁性層間の磁気結合エネルギーE_ex以外を決定するパラメータを以下のように固定し、A₁₂と B₁₂を様々に変化させ、STOの状態について計算を用いて調べた。 To demonstrate this, we calculated the STO oscillation state by reflecting the state of magnetic coupling between the magnetic layers. The magnetic coupling state of the laminated film composed of the first magnetic layer 10 / intermediate layer 11 / second magnetic layer 12 includes anisotropic energy E _ani , Zeeman energy E _zeeman , demagnetizing field energy E _demag , and magnetic layers. Using the magnetic coupling energy _Eex , it is expressed by the following equation.

j is the number of the magnetic layer, and t is the thickness of the magnetic layer. Here, parameters other than the magnetic coupling energy E _ex between the magnetic layers were fixed as follows, A ₁₂ and B ₁₂ were changed in various ways, and the state of STO was examined by calculation.

The thickness of the first magnetic layer t ¹ = 3 nm,
The thickness ^t2 of the second magnetic layer is 10 nm,
Saturation magnetization M _s = 1700 emu / cm ^{3 of} the first and second magnetic layers,
Anisotropy constant K ¹ = 4 × 10 ⁵ erg / cm ^{2 of} the first magnetic layer,
Anisotropy constant K ² of the second magnetic layer = 1.5 × 10 ⁵ erg / cm ² ,
Element shape: A square with a side of 64 nm (Example 1)
In the laminated film in the first embodiment, the magnetizations of the first magnetic layer 10 and the second magnetic layer 12 are magnetically coupled orthogonally. In Example 1, the magnetic coupling energy coupled orthogonally was determined as follows.

Bilinear exchange coupling constant A ₁₂ is -0.03 erg / cm ²
Biquadratic exchange coupling constant B ₁₂ is -0.26 erg / cm ²
The biquadratic exchange coupling constant B ₁₂ is a value examined in the experiment described above in the present invention. By substituting this into the equations (1) and (3), the energy of the laminated film is obtained. With this as an initial state, a current having a current density of 10 ⁸ A / cm ² is passed from the first magnetic body 10 to the second magnetic body 12. The conduction electrons having spin flow from the second magnetic body 12 to the first magnetic body 10.

  FIG. 3A shows the oscillation state of the calculation result. Oscillation 1-A and oscillation 1-B can be observed at a higher frequency than oscillation O. From this, it was found that the laminated film in which the magnetic layer was 90 ° magnetically coupled could oscillate at a higher frequency than the antiparallel coupling. The oscillation 1-A of Example 1 oscillates at a higher frequency of 25 GHz and the oscillation 1-B of 35 GHz than the oscillation O obtained in the comparative example of antiparallel coupling. In other words, it was proved that STO using 90 ° coupling can obtain higher oscillation frequency than conventional STO. Furthermore, in the case of the comparative example, many small oscillations could be observed up to around 100 GHz in the high frequency region where oscillation could not be observed. The frequency of the terahertz wave that is the subject of the present invention is 0.1 THz to 100 THz, and this can be realized.

  FIGS. 3B to 3E show the magnetization states of the magnetic layers. (b) is the initial state of the first magnetic layer 10 when not energized, (c) is the initial state of the second magnetic layer 12 when not energized, and (d) is the first state after 1000 ps after energization is started. (E) is the magnetization state of the second magnetic layer 12 after 1000 ps from the start of energization. In the initial state, the magnetization is coupled in a 90 ° relationship, but after 1000 ps, the magnetization is in an antiparallel relationship. However, this is a result of cutting out 1000 ps and does not always maintain antiparallelity. The first magnetic layer 10 and the second magnetic layer 12 interact in a complicated manner and oscillate.

(Example 2)
In Example 2, the magnetic coupling energy coupled orthogonally was determined as follows.

Bilinear exchange coupling constant A ₁₂ is -0.03 erg / cm ² ,
Biquadratic exchange coupling constant B ₁₂ is +0.26 erg / cm ²
The biquadratic exchange coupling constant B ₁₂ is a value obtained by inverting the sign using the absolute value investigated in the experiment described above in the present invention. Using this, the oscillation state of the laminated film was calculated.

FIG. 4A shows the oscillation state of the calculation result. Oscillations 2-A, 2-B, 2-C, and 2-D of Example 2 could be observed at a higher frequency than the oscillation O obtained in the comparative example of antiparallel coupling. The frequency of oscillation 2-D is 47 GHz. In other words, it was proved that STO using 90 ° coupling can obtain higher oscillation frequency than conventional STO. Furthermore, in the case of the comparative example, many small oscillations could be observed up to around 100 GHz in the high frequency region where oscillation could not be observed. The frequency of the terahertz wave that is the subject of the present invention is 0.1 THz to 100 THz, and this can be realized. Furthermore, by inverting the sign of Example 1 and the biquadratic exchange coupling constant B ₁₂ , many high-frequency oscillations can be obtained, and by examining the sign, it is suggested that oscillation at a higher frequency may be obtained. It was.

  4B to 4E show the magnetization state of each magnetic layer. (b) is the initial state of the first magnetic layer 10 when not energized, (c) is the initial state of the second magnetic layer 12 when not energized, and (d) is the first state after 1000 ps after energization is started. (E) shows the magnetization state of the second magnetic layer 1000 ps after the start of energization. In the initial state, the magnetization is coupled in a 90 ° relationship, but after 1000 ps, the magnetization is in an antiparallel relationship. However, this is a result of cutting out 1000 ps and does not always maintain antiparallelity. The first magnetic layer 10 and the second magnetic layer 12 interact in a complicated manner and oscillate.

(Example 3)
In Example 3, the magnetic coupling energy coupled orthogonally was determined as follows in the same manner as in Example 1.

Bilinear exchange coupling constant A ₁₂ is -0.03 erg / cm ² ,
Biquadratic exchange coupling constant B ₁₂ is -0.26 erg / cm ²
The difference from the first embodiment is the initial magnetization state. As shown in FIGS. 5B and 5C, a + 90 ° bond region and a −90 ° bond region were provided. Using this, the oscillation state of the laminated film was calculated.

  FIG. 5A shows the oscillation state of the calculation result. Oscillation 3-A of Example 3 oscillates at a frequency as high as 20 GHz, compared with the oscillation O obtained in the comparative example of antiparallel coupling. In other words, it was proved that STO using 90 ° coupling can obtain higher oscillation frequency than conventional STO. Furthermore, in the case of the comparative example, many small oscillations could be observed up to around 100 GHz in the high frequency region where oscillation could not be observed. The frequency of the terahertz wave that is the subject of the present invention is 0.1 THz to 100 THz, and this can be realized.

  FIGS. 5B to 5E show the magnetization states of the magnetic layers. (b) is the initial state of the first magnetic layer when not energized, (c) is the initial state of the second magnetic layer 12 when not energized, and (d) is the first state after 1000 ps after starting energization. The magnetization state of the magnetic layer 10, (e) is the magnetization state of the second magnetic layer 12 after 1000 ps from the start of energization. In the initial state, the magnetization is coupled in a relationship of ± 90 °, but after 1000 ps, the magnetization is in an antiparallel relationship. However, this is a result of cutting out 1000 ps and does not always maintain antiparallelity. The first magnetic layer 10 and the second magnetic layer 12 interact in a complicated manner and oscillate.

(Comparative example)
FIG. 6 is a sketch of an oscillation element according to a comparative example. Also in the comparative example, the magnetizations of the first magnetic layer 10 and the second magnetic layer 12 are coupled antiparallel. When Cr is used for the bonding interlayer,
Bilinear exchange coupling constant A ₁₂ is -0.8 erg / cm ² ,
Biquadratic exchange coupling constant B ₁₂ is -0.03 erg / cm ²
It is. By substituting this into the equations (1) and (3), the energy of the laminated film is obtained. With this as an initial state, a current having a current density of 10 ⁸ A / cm ² is passed from the first magnetic body 10 to the second magnetic body 12. The conduction electrons having spin flow from the second magnetic body 12 to the first magnetic body 10.

  FIG. 7A shows a calculation result of an oscillation state in which the horizontal axis represents frequency and the vertical axis represents oscillation intensity. If it oscillates, it can be observed as a peak. In FIG. 7A, the strong peak is at a frequency of about 15 GHz, and it can be seen that oscillation occurs at this frequency. This oscillation is referred to as “oscillation O”. This oscillation 0 is smaller than the oscillation frequency of any of the oscillations 1-A, 1-B, 2-A, 2-B, 2-C, and 3-A in the first to third embodiments. It is far from a terahertz wave with a frequency of 0.1 THz to 100Htz. Further, unlike the other embodiments, since a small oscillation cannot be observed near 0.1 THz, it can be understood that this embodiment is inappropriate as an embodiment of the present invention.

  7B to 7E show the magnetization states of the magnetic layers. (b) is an initial state of magnetization of the first magnetic layer 10 when not energized, (c) is an initial state of magnetization of the second magnetic layer 12 when not energized, and (d) is 1000 ps after energization is started. The subsequent magnetization state of the first magnetic layer 10, (e) is the magnetization state of the second magnetic layer 1000 ps after starting energization. The magnetization that was completely antiparallel in the initial state from (b) and (c) remains relatively antiparallel even when oscillation starts from (d) and (e). However, this is a result of cutting out 1000 ps and does not always maintain antiparallelity. The first magnetic layer 10 and the second magnetic layer 12 oscillate with complex interaction.

(Second Embodiment)
FIG. 8 shows an oscillation element according to the second embodiment of the present invention. The difference from the first embodiment is that an antiferromagnetic layer is provided in addition to the laminated film described above. The antiferromagnetic layer is provided below the first magnetic layer, and the magnetization of the first magnetic layer is fixed in one direction by exchange coupling energy with the antiferromagnetic layer. IrMn, PtMn, FeMn, and NiMn are suitable for the antiferromagnetic layer. An alloy containing these as main components may also be used.

  In STO, the first magnetic layer and the second magnetic layer interact with each other, but the controllability of oscillation is improved by fixing one of the magnetizations in one direction.

(Third embodiment)
FIG. 9 shows an oscillation element according to the third embodiment of the present invention. The difference from the first embodiment is that an antiferromagnetic layer 15, a third magnetic layer 16, and an antiparallel coupling layer 17 are provided in addition to the above-described laminated film. The antiferromagnetic layer 15 fixes the magnetization of the third magnetic layer 16 in one direction. The magnetizations of the third magnetic layer 16 and the first magnetic layer 10 are coupled antiparallel through the antiparallel coupling layer 17. When the magnetizations of the first magnetic layer 10 and the third magnetic layer 16 are antiparallel, the magnetostatic energy is reduced and the magnetization of the first magnetic layer 10 is stabilized. In STO, the first magnetic layer 10 and the second magnetic layer 12 interact with each other, but the controllability of oscillation is improved by fixing one of the magnetizations in one direction.

  The third magnetic layer 16 is made of Fe, Co, Ni, or an alloy containing these. For the antiparallel coupling layer 17, Ru, Ir, Rh, or the like is used.

(Fourth embodiment)
FIG. 10 shows an oscillation element according to a fourth embodiment of the present invention. The difference from the first embodiment is that the coupling intermediate layer is composed of an oxide layer 11b and a metal layer 11a, and the metal layer 11a penetrates to connect the first magnetic layer 10 and the second magnetic layer 12. It is a point. In such a structure, the current flows concentratedly only in the metal layer 11a without passing through the oxide layer 11b, and has an effect of increasing the oscillation frequency. When this structure is used in combination with high frequency using 90 ° magnetic coupling, a synergistic effect can be obtained.

  As the oxide layer 11b, an oxide obtained by oxidizing at least one of Al, Mg, Zr, Fe, Co, Ni, Cr, Mn, and Zn can be used. The metal layer 11a is made of an unoxidized region of Al, Mg, Zr, Fe, Co, Ni, Cr, Mn, or Zn, or a noble metal Cu, Au, or Ag that is not easily oxidized.

(Fifth embodiment)
FIG. 11 shows an oscillating device according to a fifth embodiment of the present invention.

First, the structure will be described. In addition to the laminated film including the first magnetic layer 10, the coupling intermediate layer 11, and the second magnetic layer 12, an antiferromagnetic layer 15, a fourth magnetic layer 18, and a nonmagnetic layer 19 are provided. An upper electrode 14 and a lower electrode 13 are formed so as to sandwich a laminated film composed of the first magnetic layer 10, the coupling intermediate layer 11, and the second magnetic layer 12. The upper electrode 14 and the lower electrode 13 are configured to pass a current perpendicular to the film surface of the laminated film.

  When the first magnetic layer 10 and the second magnetic layer 12 are not energized, their magnetizations are magnetically coupled to each other at a relative angle of +90 degrees via the coupling intermediate layer 11, and magnetically coupled to -90 degrees. A plurality of parts. In this example, as shown in FIG. 1, the second magnetic layer 12 is separated into a plurality of magnetic domains, and each is magnetically coupled at +90 degrees and −90 degrees with respect to the magnetization of the first magnetic layer 10. It is a configuration.

  The antiferromagnetic layer 15 fixes the magnetization of the fourth magnetic layer 18 in one direction. A nonmagnetic layer 19 exists between the fourth magnetic layer 18 and the first magnetic layer 10, and the magnetic coupling between the magnetization of the first magnetic layer 10 and the magnetization of the fourth magnetic layer 18 is very weak, The magnetization of the first magnetic layer 10 changes independently of the fourth magnetic layer 18, and the electrical resistance of the oscillation element changes depending on the relative angle.

The fourth magnetic layer 18 is made of Fe, Co, Ni, or an alloy containing these. As the nonmagnetic layer 19, a nonmagnetic layer having a large electric resistance change amount is suitable. Cu, Au, Ag, Al, Al ₂ O ₃ , MgO, etc. are used.

  The operation will be described. The magnetization of the first magnetic layer 10 and the magnetization of the second magnetic layer 12 are 90 ° magnetically coupled via the coupling intermediate layer 11, and a precession occurs while passing a current over a threshold value. The magnetizations of the first magnetic layer 10 and the fourth magnetic layer 18 are independent, and the electric resistance of the oscillation element changes depending on the relative angle. When the magnetization of the first magnetic layer 10 precesses, the relative angle between the magnetization of the first magnetic layer 10 and the magnetization of the fourth magnetic layer 18 changes at a high frequency, and a large oscillation intensity is obtained.

(Sixth embodiment)
FIG. 12 shows an oscillation element according to the sixth embodiment of the present invention.

First, the structure will be described. In addition to the laminated film including the first magnetic layer 10, the coupling intermediate layer 11, and the second magnetic layer 12, an antiferromagnetic layer 15, a fourth magnetic layer 18, and a nonmagnetic layer 19 are provided. An upper electrode 14 and a lower electrode 13 are formed so as to sandwich a laminated film composed of the first magnetic layer 10, the coupling intermediate layer 11, and the second magnetic layer 12. The upper electrode 14 and the lower electrode 13 are configured to pass a current perpendicular to the film surface of the laminated film.

  When the first magnetic layer 10 and the second magnetic layer 12 are not energized, their magnetizations are magnetically coupled to each other at a relative angle of +90 degrees via the coupling intermediate layer 11, and magnetically coupled to -90 degrees. A plurality of parts. In this example, as shown in FIG. 1, the second magnetic layer 12 is separated into a plurality of magnetic domains, and each is magnetically coupled at +90 degrees and −90 degrees with respect to the magnetization of the first magnetic layer 10. It is a configuration.

  The antiferromagnetic layer 15 fixes the magnetization of the fourth magnetic layer 18 in one direction. A nonmagnetic layer 19 exists between the fourth magnetic layer 18 and the first magnetic layer 10, and the magnetic coupling between the magnetization of the first magnetic layer 10 and the magnetization of the fourth magnetic layer 18 is very weak, The magnetization of the first magnetic layer 10 changes independently of the fourth magnetic layer 18, and the electrical resistance of the oscillation element changes depending on the relative angle.

  The fourth magnetic layer 18 is made of Fe, Co, Ni, or an alloy containing these. The nonmagnetic layer 19 includes an oxide layer 19b and a metal layer 19a, and the metal layer 19a penetrates to connect the first magnetic layer 10 and the fourth magnetic layer 18. The oxide layer is made of an oxide obtained by oxidizing at least one of Al, Mg, Zr, Cr, Mn, and Zn, and the metal layer is made of Cu, Au, Ag, Al, so that the electrical resistance change amount becomes large. At least one of Mg, Zr, Cr, Mn, and Zn is used.

  The operation will be described. The magnetization of the first magnetic layer and the magnetization of the second magnetic layer are 90 ° magnetically coupled via the coupling intermediate layer, and a current exceeding a threshold value flows and precesses. The magnetizations of the first magnetic layer and the fourth magnetic layer are independent, and the electric resistance of the oscillation element changes depending on the relative angle. When the magnetization of the first magnetic layer precesses, the relative angle between the magnetization of the first magnetic layer and the magnetization of the fourth magnetic layer changes at a high frequency, and a large oscillation intensity is obtained.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 10 1st magnetic layer 11 coupling | bonding intermediate | middle layer 11a metal layer 11b oxide layer 12 2nd magnetic layer 13 lower electrode 14 upper electrode 15 antiferromagnetic layer 16 3rd magnetic layer 17 antiparallel coupling layer 18 4th magnetic layer 19 Nonmagnetic layer

Claims (9)

Between the first magnetic layer having magnetization fixed in one direction, the second magnetic layer having the first magnetic domain and the second magnetic domain, and between the first magnetic layer and the second magnetic layer A laminated film composed of a bonding intermediate layer to be inserted;
An electrode for passing an electric current perpendicular to the film surface of the laminated film with respect to the laminated film;
Comprising
When the laminated film is not energized , the relative angle between the magnetization of the first magnetic layer and the magnetization of the first magnetic domain is + 90 °, and the magnetization of the first magnetic layer and the magnetization of the second magnetic domain Relative angle to -90 ° ,
An oscillation element that oscillates electromagnetic waves or light by oscillating the magnetization of the second magnetic layer when the laminated film is energized .   The oscillation element according to claim 1, wherein the coupling intermediate layer includes an oxide including at least one of Fe, Co, Ni, Cr, Mn, and Zn.   The coupling intermediate layer includes an oxide layer and a metal layer including at least one of Al, Mg, Zn, Fe, Co, Ni, Cr, Mn, and Zn, and the metal layer is the first magnetic layer. The oscillation element according to claim 1, wherein the second magnetic layer is connected to the oscillation element. Said first magnetic layer, the oscillation device according to any one of claims 1 to 3 in which the magnetization is fixed in one direction in the plane.   The oscillation element according to any one of claims 1 to 4, wherein a current direction is a direction in which the current flows from the first magnetic layer to the second magnetic layer through the coupling intermediate layer. The oscillation element according to claim 1, wherein the first magnetic domain and the second magnetic domain are plural. The laminated film includes an antiparallel coupling layer in contact with a surface opposite to a surface in contact with the coupling intermediate layer of the first magnetic layer;
A third magnetic layer in contact with a surface opposite to the surface in contact with the first magnetic layer of the antiparallel coupling layer;
An antiferromagnetic layer in contact with a surface opposite to the surface in contact with the antiparallel coupling layer of the third magnetic layer;
The antiferromagnetic layer is made of an alloy containing any one of IrMn, PtMn, FeMn, and NiMn, and the antiparallel coupling layer has any one of Ru, Ir, and Rh, and the antiparallel coupling The oscillation element according to claim 1, wherein the magnetization of the first magnetic layer and the magnetization of the third magnetic layer are antiparallel to each other by the layer. The laminated film includes a nonmagnetic layer in contact with a surface opposite to the surface in contact with the coupling intermediate layer of the first magnetic layer;
A fourth magnetic layer in contact with a surface opposite to the surface in contact with the first magnetic layer of the nonmagnetic layer;
An antiferromagnetic layer in contact with a surface opposite to the surface in contact with the nonmagnetic layer of the fourth magnetic layer, the nonmagnetic layer comprising Cu, Au, Ag, Al, Al ₂ O ₃ , MgO The oscillation element according to claim 1, comprising any one of the above. The laminated film includes a nonmagnetic layer in contact with a surface opposite to the surface in contact with the coupling intermediate layer of the first magnetic layer;
A fourth magnetic layer in contact with a surface opposite to the surface in contact with the first magnetic layer of the nonmagnetic layer;
An antiferromagnetic layer in contact with a surface opposite to the surface in contact with the nonmagnetic layer of the fourth magnetic layer, the nonmagnetic layer comprising at least one of Al, Mg, Zr, Cr, Mn, Zn An oxide including one and a metal layer including at least one of Cu, Au, Ag, Al, Mg, Zr, Cr, Mn, Zn,
The oscillation element according to claim 1, wherein the metal layer connects the first magnetic layer and the fourth magnetic layer.

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