JP2012060033A - Spin wave element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spin wave element that capable of integrating spin waves of a spin wave element, and capable of suppressing mutual interference between spin waves generated by the spin wave element.SOLUTION: A spin wave element includes: a substrate; an electrode layer disposed on the substrate; a multi layered film disposed on the electrode layer and including a first ferromagnetic layer whose magnetization is in the lamination direction or the direction perpendicular to the lamination direction; a second ferromagnetic layer disposed on a first region on the multi layered film; an intermediate layer disposed on the second ferromagnetic layer; a third ferromagnetic layer disposed on the intermediate layer; a detection part disposed on a second region on the multi layered film disposed apart from the first region on the multi layered film; a first electrode disposed on the third ferromagnetic layer; and a second electrode disposed on the detection part.

Description

  Embodiments described herein relate generally to a spin wave device.

CMOS (Complementary Metal Oxide Semiconductor), which has supported the flow of advanced information technology, has problems related to the physical limit of processing size, power consumption, and the like.

As a device replacing CMOS, a spin wave device using a magnetic material has been studied. Unlike a CMOS circuit, a spin wave device uses a phenomenon (spin wave) in which a fluctuation of magnetization induced in a magnetic material is transmitted for signal transmission. The spin wave device is composed of a spin wave medium including a magnetic film for propagating the spin wave, a spin wave generating unit for exciting the spin wave in the spin wave medium, and a detection unit for detecting the spin wave.

Phys. Rev. Lett., 89 (2002) 2370202-1. ACM Journal on Emerging Technologies in Computing Systems, Vol. 3, No. 2 (2007). J. Slonczewski: J.Magn. Magn. Mater., 159 (1996) L1.

As a structure for exciting a spin wave, there is a means for providing a line-shaped transmission line on the spin wave medium and exciting the spin wave with a magnetic field generated by passing a current through the transmission line. However, this structure is not suitable for use as a multi-input electrode because the transmission line takes up an area, and it is difficult to suppress power consumption required for excitation. Interference between transmission lines is also a big issue.

Therefore, according to an embodiment of the present invention, it is an object to provide a spin wave device that requires a small amount of power for excitation and can excite a short wavelength spin wave to increase the number of types of computation. Another object is to provide a spin wave device suitable for integration.

A spin wave device according to one embodiment of the present invention is provided with a substrate, an electrode layer provided over the substrate, and the electrode layer, and the magnetization is in a stacking direction or a direction perpendicular to the stacking direction. A multilayer film including a first ferromagnetic layer; a second ferromagnetic layer provided in a first region on the multilayer film; an intermediate layer provided on the second ferromagnetic layer; A third ferromagnetic layer provided on an intermediate layer; a detection unit provided in a second region on the multilayer film provided apart from the first region on the multilayer film; A first electrode provided on a third ferromagnetic layer, and a second electrode provided on the detection unit, wherein the second ferromagnetic layer or the third ferromagnetic layer One of the magnetizations is variable, the other magnetization is fixed in one direction, the film thickness of the magnetization free layer is t, and the center of gravity of the magnetization free layer is When the distance to the edge is ^r, and satisfies a relation is r> 0.27t 2 -1.9t + 13.

The figure which shows the spin wave element which concerns on 1st Embodiment. The figure which shows the spin wave element which concerns on 1st Embodiment. The figure which shows the spin wave element which concerns on 1st Embodiment. The figure which shows an input part. The figure which shows an input part. The figure which shows an input part. The figure which shows a reflux magnetic domain. The figure which shows a magnetization free layer. The figure which shows the spin wave element which concerns on 2nd Embodiment. The figure which shows the spin wave element which concerns on 2nd Embodiment. The figure which shows the modification of a spin wave element. The figure which shows the modification of a spin wave element. The figure which shows the modification of a spin wave element. The figure which shows the modification of a spin wave element. The figure which shows the spin wave element which concerns on 3rd Embodiment. The figure which shows the Example of a spin wave element. The figure which shows the Example of a spin wave element. The figure which shows the Example of a spin wave element. The figure which shows the Example of a spin wave element. The figure which shows the Example of a spin wave element. The figure which shows the Example of a spin wave element. The figure which shows the Example of a spin wave element.

Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals denote the same items. Note that the drawings are schematic or conceptual, 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 actual ones. 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 diagram showing a spin wave device 10.

The upper diagram of FIG. 1 shows a view of the multilayer film 30 constituting the spin wave element 10 as viewed from the direction perpendicular to the plane of the spin wave element 10 (stacking direction of the multilayer film 30). 1 shows a cross-sectional view of the spin wave device 10.

As shown in the lower diagram of FIG. 1, the spin wave device 10 is provided with an electrode layer 25 on a substrate 20. A multilayer film 30 is provided on the electrode layer 25. A detection unit 50 and a plurality of input units 40 are provided on the multilayer film 30, and the input unit 40 and the detection unit 50 are separated via a nonmagnetic layer 70. Electrodes 80 and 90 are provided on the input unit 40 and the detection unit 50. A nonmagnetic insulating layer 60 is formed on the electrode layer 25 so as to surround the multilayer film 30. That is, the nonmagnetic insulating layer 60 covers the multilayer film 30 in a direction perpendicular to the stacking direction of the multilayer film 30. The multilayer film 30 includes a layer in which magnetization is directed in a direction parallel to the stacking direction of the multilayer film 30 (magnetization is directed in the stacking direction). A region where the input unit 40 is provided on the multilayer film 30 is defined as a first region. A region where the detection unit 50 is provided on the multilayer film 30 is defined as a second region.

As shown in the upper diagram of FIG. 1, the spin wave device 10 is provided with a plurality of input units 40 for one detection unit 50.

In the upper diagram of FIG. 1, the outer edge of the multilayer film 30 has an elliptical shape. However, the shape of the multilayer film 30 is not limited to an elliptical shape, and may be a circular shape or a rectangular shape.

Further, the input unit 40 may be provided between the input unit 40 and the detection unit 50.

FIG. 2 is a diagram showing the structure of the multilayer film 30 of the spin wave device 10. The multilayer film 30 has a structure in which a nonmagnetic layer 31, a ferromagnetic layer 32, and a nonmagnetic layer 33 are provided in this order. A region where the input unit 40 is provided on the nonmagnetic layer 33 is defined as a first region. A region where the detection unit 50 is provided on the nonmagnetic layer 33 is defined as a second region.

For the substrate 20, for example, Si can be used. The substrate 20 may be a CMOS. In this case, the electrode layer 25 can be omitted.

For the electrode layer 25, for example, copper (Cu), gold (Au), silver (Ag), or aluminum (Al) can be used. You may use as an alloy containing at least 2 types from these elements. Further, at least one of these elements may be selected and combined with other elements to form an alloy.

For the nonmagnetic layers 31 and 33, for example, Ta, Ru, Pt, Pd, Ir, Cu, Au, Ag, Cr, or Al can be used. An alloy containing at least two of these elements may be used. Further, at least one of these elements may be selected and combined with other elements to form an alloy. You may use these elements as laminated structure. A nonmagnetic insulator such as MgO, alumina (Al ₂ O ₃ ), or SiO ₂ can also be used.

The ferromagnetic layer 32 is a layer whose magnetization is oriented in a direction perpendicular to the in-plane direction (stacking direction). For the ferromagnetic layer 32, for example, FeVPd, FeCrPd, CoFePt, or the like can be used. That is, it is made of a magnetic metal containing at least one element selected from iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), and chromium (Cr). In addition, at least one element selected from iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), and chromium (Cr), platinum (Pt), palladium (Pd), and iridium (Ir) An alloy of a combination with at least one element selected from ruthenium (Ru) and rhodium (Rh) can be used. These properties can be adjusted by the composition of the constituent magnetic material and heat treatment. In addition, rare earth-transition metal amorphous alloys such as TbFeCo and GdFeCo, or a laminated structure of Co / Pt, Co / Pd, and Co / Ni are also desirable. Furthermore, Co / Ru, Fe / Au, Ni / Cu, etc., which become perpendicular magnetization in combination with the nonmagnetic layers 31 and 33, can be used by controlling the crystal orientation of the film. If the ferromagnetic layer 32 is made of yttrium iron garnet, manganese ferrite, or ferrite oxide such as γ-iron oxide, the loss of spin waves can be reduced. Furthermore, the functionality can be improved by using a magnetic semiconductor.

The detector 50 includes, for example, copper (Cu), gold (Au), silver (Ag), aluminum (Al), platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), or tungsten ( W) can be used. Moreover, you may combine these elements. An alloy containing at least two of these elements may be used. Further, at least one of these elements may be selected and combined with other elements to form an alloy. Carbon nanotubes and carbon nanowires can also be used.

The shape of the input unit 40 is a dot shape such as a circle, an ellipse, or a polygon. A spherical wave-like spin wave is generated at the input unit 40 by using a dot shape. As for the size of the input unit 40, it is desirable in terms of magnetic domain control that the maximum diameter of the contact surface between the input unit 40 and the multilayer film 30 is 500 nm or less, and further 100 nm or less is necessary for excitation efficiency and integration. desirable. The minimum diameter of the contact surface is preferably 1 nm. If it is smaller than 1 nm, the energy for exciting the spin wave increases, which is not preferable. Here, “diameter” means the length of the long axis when the dot shape is elliptical, and means the length of the diagonal line when the dot shape is rectangular or polygonal.

The shape of the detection unit 50 may be a dot shape such as a circle, an ellipse, a quadrangle, or a polygon. The size (average diameter) of the detection unit 50 is preferably different from the wavelength of the spin wave transmitted through the ferromagnetic layer 32. This is because if the wavelength of the spin wave and the size of the detection unit 50 are the same, the spin wave may be canceled on the detection unit 50 side.

For the nonmagnetic insulating layer 60, for example, SiO ₂ , Al ₂ O ₃ , MgO, AlN, SiNO, or the like can be used.

The same material as the nonmagnetic insulating layer 60 can be used for the nonmagnetic layer 70. Use of the same material as that of the nonmagnetic insulating layer 60 is preferable because manufacturing becomes easy. In addition, when using near-field light for output as described later, for example, Au (gold), Pt (platinum), Ir (iridium), Cu (copper), or an alloy containing at least two of these elements The nonmagnetic metal can be used. Further, at least one of these elements may be selected and used as a nonmagnetic metal as an alloy in combination with other elements.

For the electrodes 80 and 90, a conductive magnetic material or a nonmagnetic material is used.

As the magnetic material, an in-plane magnetization film having an easy axis of magnetization substantially parallel to the film surface or a perpendicular magnetization film having a perpendicular axis can be used. As the in-plane magnetization film, for example, a magnetic metal containing at least one element selected from iron (Fe), cobalt (Co), and nickel (Ni) can be used. As the perpendicular magnetization film, the same material as that of the ferromagnetic layer 32 can be used.

As the nonmagnetic material, copper (Cu), gold (Au), silver (Ag), or aluminum (Al) can be used. Moreover, it is good also as an alloy combining these elements. Furthermore, as the nonmagnetic material, a material such as carbon nanotube, carbon nanowire, or graphene can be used.

FIG. 3 is a diagram illustrating the input unit 40.

The input unit 40 has a structure in which the intermediate layer 38 is sandwiched between the magnetization fixed layer 37 and the magnetization free layer 39.

The magnetization pinned layer 37 and the magnetization free layer 39 are made of a magnetic metal containing at least one element selected from iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), and chromium (Cr). . Further, the magnetization pinned layer 37 and the magnetization free layer 39 are ferromagnetic.

For the intermediate layer 38, for example, Cu having a long spin diffusion length can be used.

In FIG. 3, the magnetization free layer 39 is provided on the nonmagnetic layer 33. However, as shown in FIG.

As shown in FIG. 4, the magnetization direction of either one of the magnetization fixed layer 37 and the magnetization free layer 39 is parallel to the stacking direction, and the other layer has a magnetization direction relative to the stacking direction. It is vertical. The magnetization pinned layer 37 has the magnetization direction fixed in one direction. The magnetization direction of the magnetization free layer 39 is variable. When the direction of magnetization is parallel to the stacking direction, there are two cases: upward on the paper and downward on the paper.

As shown in FIG. 5, the shape of the input unit 40 may be a tapered shape or a reverse tapered shape with respect to the stacking direction.

FIG. 6 is a bird's-eye view of the input unit 40. The film thickness t (nm) of the magnetization free layer 39 and the distance r (nm) from the center of gravity of the film surface of the magnetization free layer 39 to the outer edge of the magnetization free layer 39 satisfy the following Expression 1. The distance r is preferably a radius. In FIG. 6, the input unit 40 has a cylindrical shape. However, the shape is not limited to this, and may be an elliptical shape, a rectangular shape, or the like.

r> 0.27t ² −1.9t + 13 (Formula 1)

FIG. 7 is a diagram for explaining a conceptual diagram of a return magnetic domain (also referred to as vortex).

Under the condition of Formula 1, when a current is passed through the input unit 40 in the stacking direction, a return magnetic domain is formed in the magnetization free layer 39, and a core is formed at the center of the return magnetic domain. The core means that the magnetization stands at the center of the return magnetic domain. In the reflux magnetic domain, there are a mode in which the core is fixed to the center in the plane of the magnetization free layer 39 (lower diagram in FIG. 7) and a mode in which the outer periphery of the magnetization free layer 39 is rotated (upper diagram in FIG. 7). The former is called reflux magnetic domain fixation, and the latter is called reflux magnetic domain oscillation. The return magnetic domain oscillation and the return magnetic domain fixation are determined by the magnitude of the current value flowing through the input unit 40.

As can be seen from FIG. 7, it is understood that a core having a size smaller than the distance from the center of gravity of the film surface of the magnetization free layer 39 to the outer periphery is formed in both the return magnetic domain oscillation and the return magnetic domain fixation.

Normally, the magnetization of the magnetization free layer 39 is oriented in an arbitrary direction as shown in FIG. 7A. When a current is passed through the magnetization free layer 39 in the stacking direction, the magnetization preferentially moves without creating a return magnetic domain, so that the ferromagnetic layer 32 has a wavelength of about the major axis of the magnetization free layer 39. Spin waves will be excited. On the other hand, according to the spin wave element 10, a reflux magnetic domain is created, and thereby the wavelength of the spin wave excited by the magnetic field or the spin torque is about the core diameter of the reflux magnetic domain. Since the spin wave device 10 can be used to superimpose short wavelength spin waves, the types of calculations can be increased.

When a certain current value is reached, initially a return magnetic domain oscillation occurs. Furthermore, when a large current value is reached, the reflux magnetic domain sticking occurs.

About the conditions which a return magnetic domain generate | occur | produces, it can derive | lead-out as the following formula 2 by using a LLG (Landau-Liftshitz-Gilbert) equation (for example, refer nonpatent literature 3).

J _c is the current density, the _{M s} magnetization, t the _{thickness, H pin} leakage magnetic field from the pinned layer 37, g (θ) indicates a spin torque efficiency in a model of Slonczewski. It is allowed to flow a current larger than the current density J _c shown in Equation 2, closure domain is generated.

When Ru is used for the nonmagnetic layer 33, the spin torque that contributes to the return magnetic domain oscillation and the return magnetic domain pinion is only the electrons polarized by the pinned magnetic layer 37. To increase efficiency. This is because the contribution of the spin torque derived from the multilayer film 30 can be reduced in order to make the directions of the electrons whose spin has been spin-polarized uneven.

Next, the operation principle of the spin wave device 10 according to the present embodiment will be described.

A current flows from the electrode 80 toward the electrode layer 25 via the input unit 40. At this time, the magnetization free layer 39 forms a reflux magnetic domain. When oscillating in the reflux magnetic domain, the magnetization in the ferromagnetic layer 32 starts precessing due to magnetic field excitation. This precession of magnetization is propagated one after another in the ferromagnetic layer 32 to generate spin waves. This spin wave spreads in the plane of the ferromagnetic layer 32 as a spherical wave because the input part 40 has a dot shape. On the other hand, in the case of the fixed free domain, electrons are spin-polarized by the core formed in the magnetization free layer 39, and the magnetization in the ferromagnetic layer 32 starts precession due to the spin torque. This precession of magnetization is propagated one after another in the ferromagnetic layer 32 to generate spin waves. When Ru is used for the nonmagnetic layer 33, the magnetization in the ferromagnetic layer 32 is excited by the magnetic field by the core formed in the magnetization free layer 39 and starts precession.

Then, the spin wave generated in the ferromagnetic layer 32 on the input unit 40 side is transmitted to the detection unit 50 side. At this time, a potential is generated in the detection unit 50 by an induced electromotive force or a combination of the spin pumping effect and the inverse spin Hall effect. By detecting this, a spin wave is detected. Note that the spin pumping effect and the inverse spin Hall effect refer to a phenomenon in which a spin wave is absorbed as a spin-polarized electron by a nonmagnetic metal and the potential is changed by scattering the spin-polarized electron.

Next, an example of a method for manufacturing the spin wave device 10 will be described.

First, after forming the electrode layer 25 on the substrate 20, these are placed in an ultra-high vacuum sputtering apparatus.

Next, a nonmagnetic layer 31, a ferromagnetic layer 32, and a nonmagnetic layer 33 are formed in this order on the electrode layer 25 formed on the substrate 20. The multilayer film 30 is formed so far. A magnetization free layer 39, an intermediate layer 38, and a magnetization pinned layer 37 are formed thereon. In order to prevent oxidation, a cap layer is provided on the magnetization pinned layer 37. By annealing in a magnetic field, the magnetization of the ferromagnetic layer 32 and the pinned layer 37 is directed in a direction parallel to the stacking direction.

A resist is applied on the cap layer, and the resist is exposed and developed using a stepper exposure apparatus. At this time, the resist is patterned into a desired shape. Further, the periphery of the input unit 40, the output unit 50, the nonmagnetic layer 31, the ferromagnetic layer 32, and the nonmagnetic layer 33 is shaved by ion milling to form the multilayer film 30.

Next, the nonmagnetic insulating layer 60 is formed on the substrate 20 and the mask. Thereafter, the mask formed on the cap layer is removed, and the nonmagnetic layer 70 is formed on the nonmagnetic insulating layer 60 and the multilayer film 30.

Next, an electron beam resist is applied on the nonmagnetic layer 70 and the cap layer, and electron beam exposure is performed to form a mask corresponding to the input unit 40 and the detection unit 50. Then, the input unit 40 and the detection unit 50 are formed by ion milling until the nonmagnetic layer 33 is exposed using the formed mask. Subsequently, an insulating film is formed so as to insulate and bury the input unit 40 and the detection unit 50, and the resist mask is lifted off.

Next, a resist is applied on the nonmagnetic layer 70, the input unit 40, and the detection unit 50. The resist is patterned using a KrF stepper exposure apparatus, and openings for connecting the electrodes 80 and 90 to the input unit 40 and the detection unit 50 are formed in the resist. Then, after forming a metal film and filling the opening with the metal, the resist is removed to form the electrodes 80 and 90, whereby the spin wave device 10 is manufactured.

The electrodes 80 and 90 are subsequently provided with wirings for electrical input / output.

According to the spin wave device 10, a spin wave can be generated with a size smaller than that of the input unit 40.

The spin wave element can constitute an adder, an information processing device, a signal processing device, or the like. When a spin wave element is used for the adder, a plurality of input units are provided, and a superposition of spin waves generated from the plurality of input units is detected by the detection unit. When a spin wave element is used as a signal processing device, for example, a positive current is passed through the spin wave element for an input having a value of “1” and a current is applied to an input having a value of “0”. Signal processing is performed by not letting it flow.
(Second Embodiment)

FIG. 8 is a diagram showing the spin wave device 100.

The spin wave element 100 is different from the spin wave element 10 in that the magnetization of the ferromagnetic layer 110 is oriented in a direction perpendicular to the stacking direction (a direction parallel to the in-plane direction). By making the ferromagnetic layer 110 into a shape having a longitudinal direction, the magnetization of the ferromagnetic layer 110 can be fixed in the longitudinal direction.

The ferromagnetic layer 110 is made of, for example, a magnetic metal containing at least one element selected from iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), and chromium (Cr).

Further, as shown in FIG. 9, an antiferromagnetic layer 120 may be provided between the electrode layer 25 and the nonmagnetic layer 31. By providing the antiferromagnetic layer 120, the magnetization direction of the ferromagnetic layer 110 is stabilized in the in-plane direction.

As the material of the antiferromagnetic layer 120, Fe—Mn, Pt—Mn, Pt—Cr—Mn, Ni—Mn, Pd—Mn, Pd—Pt—Mn, Ir—Mn, Pt—Ir—Mn, NiO, Fe ₂ O ₃ , a magnetic semiconductor, or the like can be used.

In such a case, a tunnel insulating film material or a nonmagnetic metal material can be used for the nonmagnetic layer 31.

Examples of the tunnel insulating film material include aluminum (Al), titanium (Ti), zinc (Zn), zirconium (Zr), tantalum (Ta), cobalt (Co), nickel (Ni), silicon (Si), magnesium ( An oxide, nitride, fluoride, oxynitride, or the like containing at least one element selected from Mg) and iron (Fe) can be used. In addition, a semiconductor material having a large energy gap such as AlAs, GaN, AlN, ZnSe, ZnO, and MgO can be used. When a tunnel insulating film material is used, it is desirable that the thickness is about 0.2 nm to 2.0 nm in order to reduce the resistance.

Nonmagnetic metal materials include, for example, copper (Cu), gold (Au), silver (Ag), aluminum (Al), ruthenium (Ru), iridium (Ir), osmium (Os), tungsten (W), and tantalum. (Ta) or platinum (Pt) can be used. Moreover, it is good also as an alloy combining these elements. In this case, the film thickness of the nonmagnetic layer 31 is preferably 1.5 nm or more and 20 nm or less.
(Modification 1)

FIG. 10 is a diagram illustrating an input unit 41 that is a modification of the input unit 40 of the spin wave device 10.

A protective layer 71 is provided on the nonmagnetic layer 33 so as to sandwich the side surface of the input unit 41. A shield 72 is provided so as to further sandwich the protective layer 71. That is, the side surface of the input unit 41 is covered with the protective layer 71, and the protective layer 71 is further covered with the shield 72.

For the protective layer 71, for example, Al (aluminum), Ti (titanium), Zn (zinc), Zr (zirconium), Ta (tantalum), Co (cobalt), Ni (nickel), Si (silicon), Mg (magnesium) ), And an oxide, nitride or fluoride containing at least one element selected from Fe (iron). _{Specifically, Al 2 O 3, SiO 2} , MgO, AlN, Ta-0, Al-Zr-O, Bi 2 O 3, MgF 2, CaF 2, SrTiO 3, AlLaO 3, AlN-O, Si—N—O can be used.

The protective layer 71 can be made of a nonmagnetic semiconductor. The nonmagnetic semiconductor is ZnOx, InMn, GaN, GaAs, TiOx, Zn, Te, or the like. Moreover, you may dope a transition metal to a nonmagnetic semiconductor.

The shield 72 includes, for example, at least one element selected from Fe, Co, Ni, Mn, and Cr, Pt (platinum), Pd (palladium), Ir (iridium), Ru (ruthenium), and Rh (rhodium). An alloy of a combination with at least one element selected from the above can be used. For the shield 72, a rare earth-transition metal amorphous alloy such as TbFeCo or GdFeCo, or a laminated structure of Co / Pt, Co / Pd, or Co / Ni may be used.

According to the present modification, a leakage magnetic field from the input unit 41 can be prevented, so that a plurality of input units 41 can be provided adjacent to each other. As a result, a multi-input operation by a plurality of input units can be performed.
(Modification 2)

FIG. 11 is a diagram illustrating a detection unit 51 that is a modification of the detection unit 50 of the spin wave element 10.

The detection unit 51 is different from the detection unit 50 of the spin wave device 10 in that a ferromagnetic layer 35 and an antiferromagnetic layer 34 are provided in the detection unit 51.

The magnetization of the ferromagnetic layer 35 is oriented in a direction parallel to or perpendicular to the stacking direction of the multilayer film 30 (in-plane direction). The same material as the ferromagnetic layer 32 can be used for the ferromagnetic layer 35.

The same material as the antiferromagnetic layer 120 can be used for the antiferromagnetic layer 34.
(Modification 3)

FIG. 12 is a diagram illustrating a detection unit 52 that is a modification of the detection unit 50 of the spin wave element 10.

The detection unit 52 is different from the detection unit 50 of the spin wave device 10 in that the magnetization fixed layer 37 and the magnetization free layer 39 are provided in the detection unit 52 with the intermediate layer 38 interposed therebetween.
(Modification 4)

FIG. 13 is a view showing a modification of the spin wave device 10. FIG. 13 is a view of the spin wave device 10 as viewed from above.

As shown in FIG. 13, the path connecting the input unit 40 and the detection unit 50 may be a thin line extending in one direction.
(Third embodiment)

FIG. 14 is a diagram showing the spin wave device 200.

The spin wave element 10 is different from the spin wave element 10 in that it is a detection unit in which one signal line is sandwiched between two ground lines. FIG. 14 shows the spin wave device 200 viewed from above. Only one ground wire may be placed on one side.

The spin wave device 200 can detect a spin wave by an induced electromotive force.

A conductive magnetic material or a non-magnetic material can be used for the ground line and the signal line.

Nonmagnetic materials include at least one element selected from Au, Cu, Cr, Zn, Ga, Nb, Mo, Ru, Pd, Ag, Hf, Ta, W, Pt, Bi, and Al, or an alloy thereof. Can be used. In addition, as the nonmagnetic material, carbon nanotubes, carbon nanowires, graphene, or the like can be used.
Example 1

The input unit 40 was designed and a simulation using micromagnetics was performed. The thickness of the magnetization pinned layer 37 was 8 nm, the magnetization Ms was 1000 emu / cc, and the uniaxial magnetic anisotropy Ku was 8 Merg / cm ³ . The film thickness of the intermediate layer 38 was 8 nm and the material was Cu. The thickness of the magnetization free layer 39 was 3 nm, the magnetization Ms was 800 emu / cc, and the uniaxial magnetic anisotropy Ku was 5000 erg / cm ³ . The magnetization direction of the magnetization pinned layer 37 is assumed to be perpendicular to the in-plane direction. The magnetization direction of the magnetization free layer 39 is assumed to be parallel to the in-plane direction.

The diameter of the input unit 40 was 50 nm.

FIG. 15 is a diagram illustrating how the magnetization of the magnetization free layer 39 precesses when a current of 50 μA is passed through the input unit 40. The vertical axis indicates the amplitude of the precession of magnetization of the magnetization free layer 39. The horizontal axis represents time (ns). The current flows in a direction perpendicular to the film surface of the magnetization free layer 39.

FIG. 15 shows that the magnetization of the magnetization free layer 39 precesses. Here, the magnetization free layer 39 oscillates in the reflux magnetic domain. Such precession continued for over 100 ns.

FIG. 16 is a diagram showing the relationship between the frequency of the magnetic field generated in the magnetization free layer 39 and the current. The vertical axis represents the frequency (GHz) of the magnetic field generated in the magnetization free layer 39. The horizontal axis indicates the current (μA) flowing through the input unit 40.

From FIG. 16, it can be seen that the magnetic field generated in the magnetization free layer 39 changes depending on the value of the current flowing through the input unit 40.
(Example 2)

A configuration in which the input unit 40 was provided on the multilayer film 30 was designed, and a simulation using micromagnetics was performed. On the multilayer film 30, a magnetization free layer 39, an intermediate layer 38, and a magnetization pinned layer 37 were formed in this order. The film thickness of the ferromagnetic layer 32 was 10 nm, and the magnetization Ms was 600 emu / cc or 800 emu / cc. The thickness of the magnetization pinned layer 37 was 8 nm, the magnetization Ms was 1000 emu / cc, and the uniaxial magnetic anisotropy Ku was 8 Merg / cm ³ . The film thickness of the intermediate layer 38 was 8 nm and the material was Cu. The thickness of the magnetization free layer 39 was 3 nm, the magnetization Ms was 800 emu / cc, and the uniaxial magnetic anisotropy Ku was 5000 erg / cm ³ . The magnetization direction of the magnetization pinned layer 37 is assumed to be perpendicular to the in-plane direction. The magnetization direction of the magnetization free layer 39 is assumed to be parallel to the in-plane direction.

The diameter of the input unit 40 was 50 nm.

FIG. 17 is a diagram showing the relationship between the resonance frequency of the ferromagnetic layer 32 and the uniaxial magnetic anisotropy Ku. The vertical axis represents the resonance frequency (GHz) of the ferromagnetic layer 32. The horizontal axis represents the uniaxial anisotropy Ku (Merg / cc) of the ferromagnetic layer 32.

As described with reference to FIG. 16, when a predetermined current is passed, a magnetic field having a frequency corresponding to the predetermined current is generated from the magnetization free layer 39. FIG. 17 shows that the ferromagnetic layer 32 preferably has the uniaxial magnetic anisotropy Ku shown in FIG. 17 in order to efficiently excite spin waves with a magnetic field of this frequency. As a result, spin waves can be magnetically excited in the ferromagnetic layer 32 by reflux magnetic domain oscillation.
Example 3

A configuration in which four input units 40 were provided on the nonmagnetic layer 33 was designed, and a simulation using micromagnetics was performed. On the multilayer film 30, a magnetization free layer 39, an intermediate layer 38, and a magnetization pinned layer 37 were formed in this order. The film thickness of the nonmagnetic layer 33 was 2 nm, 3 nm, 5 nm, or 10 nm. Ru was used for the nonmagnetic layer 33. The thickness of the magnetization pinned layer 37 was 8 nm, the magnetization Ms was 1000 emu / cc, and the uniaxial magnetic anisotropy Ku was 8 Merg / cm ³ . The film thickness of the intermediate layer 38 was 8 nm and the material was Cu. The thickness of the magnetization free layer 39 was 3 nm, the magnetization Ms was 800 emu / cc, and the uniaxial magnetic anisotropy Ku was 5000 erg / cm ³ . The magnetization direction of the magnetization pinned layer 37 is assumed to be perpendicular to the in-plane direction. The magnetization direction of the magnetization free layer 39 is assumed to be parallel to the in-plane direction.

The diameter of the input unit 40 was 50 nm. An electric current was applied in the stacking direction of the input unit 40.

FIG. 18 is a diagram illustrating a state of magnetization of spin waves generated at the four input units 40 by magnetic field excitation. The upper diagram of FIG. 18 shows a state at 0 ps. The lower part of FIG. 18 shows a state after 200 ps. It can be seen that a spin wave is generated from the input unit 40.

When the film thickness of the nonmagnetic layer 33 was 2 nm, 3 nm, 5 nm, and 10 nm, the magnetic field strengths at the upper end position of the ferromagnetic layer 32 were 350 Oe, 260 Oe, 150 Oe, and 50 Oe, respectively.
Example 4

The input unit 40 was designed and a simulation using micromagnetics was performed. The thickness of the magnetization pinned layer 37 was 8 nm, the magnetization Ms was 1000 emu / cc, and the uniaxial magnetic anisotropy Ku was 8 Merg / cm ³ . The film thickness of the intermediate layer 38 was 8 nm and the material was Cu. The thickness of the magnetization free layer 39 was 3 nm, the magnetization Ms was 800 emu / cc, and the uniaxial magnetic anisotropy Ku was 5000 erg / cm ³ . The magnetization direction of the magnetization pinned layer 37 is assumed to be perpendicular to the in-plane direction. The magnetization direction of the magnetization free layer 39 is assumed to be parallel to the in-plane direction.

The diameter of the input unit 40 was 50 nm.

FIG. 19 is a diagram showing the frequency of the magnetic field generated by the magnetization free layer 39 when a current of 50 μA is passed through the input unit 40 and a magnetic field is applied from a direction perpendicular to the film surface of the magnetization free layer 39. The vertical axis represents the frequency (GHz) of the magnetic field generated by the magnetization free layer 39. The horizontal axis indicates the magnetic field strength (Oe). The current flows in a direction perpendicular to the film surface of the magnetization free layer 39.

It can be seen from FIG. 19 that the frequency of the magnetic field generated by the magnetization free layer 39 changes according to the magnetic field strength. In particular, when the magnetic field strength is −300 Oe or more and less than −200 Oe, the frequency of the magnetic field generated by the magnetization free layer 39 is constant at 6.1 GHz. However, the phase of the magnetic field is changing. That is, by setting the applied magnetic field intensity to an appropriate value, the phase of the magnetic field can be changed without changing the frequency of the magnetic field generated by the magnetization free layer 39. Thereby, since the calculation result when a spin wave overlaps can be changed, the kind of calculation can be increased. The magnetic field can be applied using a coil or the like. A current may be passed through the coil. A part of the coil may be used as an electrode.
(Example 5)

A configuration in which the input unit 40 was provided on the nonmagnetic layer 33 was designed, and a simulation using micromagnetics was performed. On the nonmagnetic layer 33, a magnetization free layer 39, an intermediate layer 38, and a magnetization pinned layer 37 were formed in this order. The film thickness of the nonmagnetic layer 33 was 3 nm. Cu was used for the nonmagnetic layer 33. The thickness of the magnetization pinned layer 37 was 8 nm, the magnetization Ms was 1000 emu / cc, and the uniaxial magnetic anisotropy Ku was 8 Merg / cm ³ . The film thickness of the intermediate layer 38 was 8 nm and the material was Cu. The thickness of the magnetization free layer 39 was 1 n, 3 nm, or 5.8 nm, the magnetization Ms was 800 emu / cc, and the uniaxial magnetic anisotropy Ku was 5000 erg / cm ³ . The magnetization direction of the magnetization pinned layer 37 is assumed to be perpendicular to the in-plane direction. The magnetization direction of the magnetization free layer 39 is assumed to be parallel to the in-plane direction.

FIG. 20 is a diagram illustrating a relationship in which a return magnetic domain is formed with respect to the thickness of the magnetization free layer 39 when a current is passed through the input unit 40 and the distance from the center of gravity of the film surface of the magnetization free layer 39 to the outer periphery. is there. The distance from the center of gravity of the film surface of the magnetization free layer 39 to the outer periphery is defined from the center of the film surface of the magnetization free layer 39 with the shape of the magnetization free layer 39 being circular. The vertical axis represents the distance (nm) from the center of gravity of the film surface of the magnetization free layer 39 to the outer periphery. The horizontal axis represents the film thickness (nm) of the magnetization free layer 39. The current flows in a direction perpendicular to the film surface of the magnetization free layer 39.

The region above the dotted line in FIG. 20 shows the range in which the magnetization free layer 39 forms a reflux magnetic field (vortex). Fitting with a quadratic function based on this dotted line. When such a fitting satisfies the relationship r> 0.27t ² −1.9t + 13, the distance r (nm) from the center of gravity of the film surface of the magnetization free layer 39 to the outer periphery thereof and the film thickness t (nm) satisfy It was found that a reflux magnetic field was formed in the magnetization free layer 39.

FIG. 21 is a diagram illustrating a state in which the magnetization of the magnetization free layer 39 stands when a current of 90 μA is passed through the input unit 40. It can be seen that the size of the core of the reflux magnetic field is constant (about 10 nm) regardless of the size of the magnetization free layer 39. The current flows in a direction perpendicular to the film surface of the magnetization free layer 39. At this time, a spin wave having a wavelength about the size of the core was excited in the ferromagnetic layer 32 by spin torque. When Ru is used for the nonmagnetic layer 33, when a current of 90 μA is passed through the input unit 40, a spin wave having a wavelength about the size of the core is magnetically excited in the ferromagnetic layer 32.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Spin wave element, 20 ... Substrate, 25 ... Electrode layer, 30 ... Multilayer film, 40 ... Input part, 50 ... Detection part, 60 ... Nonmagnetic insulating layer, 70 ... Nonmagnetic layer, 80, 90 ... Electrode

Claims (5)

A substrate,
An electrode layer provided on the substrate;
A multilayer film including a first ferromagnetic layer provided on the electrode layer and having a magnetization oriented in a stacking direction or a direction perpendicular to the stacking direction;
A second ferromagnetic layer provided in a first region on the multilayer film;
An intermediate layer provided on the second ferromagnetic layer;
A third ferromagnetic layer provided on the intermediate layer;
A detection unit provided in a second region on the multilayer film provided apart from the first region on the multilayer film;
A first electrode provided on the third ferromagnetic layer;
A second electrode provided on the detection unit;
With
The magnetization of either the second ferromagnetic layer or the third ferromagnetic layer is variable, the other magnetization is fixed in one direction, and the thickness of the magnetization free layer is t, When r is the distance from the center of gravity of the magnetization free layer to the outer edge,
r> 0.27t ² -1.9t + 13
A spin wave device characterized by satisfying the relationship: A protective layer sandwiching the input unit in a direction perpendicular to the stacking direction;
A shield sandwiching the protective layer;
The spin wave device according to claim 1, further comprising:   The second ferromagnetic layer, the intermediate layer, and the third ferromagnetic layer are input portions, and the input portion has a cylindrical shape, an elliptical column shape, or a polygonal column shape. Item 4. The spin wave device according to Item 1. A substrate,
An electrode layer provided on the substrate;
A first nonmagnetic layer provided on the electrode layer;
A first ferromagnetic layer provided on the first nonmagnetic layer and having a magnetization oriented in a stacking direction or a direction perpendicular to the stacking direction;
A second nonmagnetic layer provided on the first ferromagnetic layer;
A second ferromagnetic layer provided in a first region on the second nonmagnetic layer;
An intermediate layer provided on the second ferromagnetic layer;
A third ferromagnetic layer provided on the intermediate layer;
A detection unit provided in a second region on the second nonmagnetic layer provided apart from the first region on the second nonmagnetic layer;
A first electrode provided on the third ferromagnetic layer;
A second electrode provided on the detection unit;
With
The magnetization of either the second ferromagnetic layer or the third ferromagnetic layer is variable, the other magnetization is fixed in one direction, and the thickness of the magnetization free layer is t, When r is the distance from the center of gravity of the magnetization free layer to the outer edge,
r> 0.27t ² -1.9t + 13
A spin wave device characterized by satisfying the relationship:   The spin wave device according to claim 4, wherein the second nonmagnetic layer contains Ru.