Spin inductor

Abstract

This spin inductor includes a wiring layer, a first ferromagnetic layer in contact with a first surface of the wiring layer, and a second ferromagnetic layer in contact with a second surface facing the first surface of the wiring layer.

Description

Spin inductor

[0001] The present disclosure relates to spin inductors.

[0002] Inductors, along with resistors and capacitors, are major electronic components used in a variety of electronic devices. A coil is one example of an inductor. There is a trade-off between the size of a coil and the strength of its inductance, and it is difficult to achieve large inductance with a small coil.

[0003] In recent years, attention has been focused on new types of inductors that do not use coils. New types of inductors that do not use coils are sometimes called emergent inductors. For example, Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2 disclose new inductors that utilize spin vibrations (hereinafter referred to as spin inductors). Spin inductors have attracted attention because the smaller the element size, the stronger the inductance strength, making it possible to achieve both miniaturization and inductance strength.

[0004] International Publication No. 2022 / 181069

[0005] Yuta Yamane, Shunsuke Fukami, and Junichi Ieda, Physical Review Letters 128,147201 (202).Yasufumi Arai and Jun'ichi Ieda, Journal of the Physical Society of Japan 92, 074705 (2023).

[0006] There is a demand for inductors that are small and have large inductance. To achieve both of these characteristics, there is a demand for inductors that can provide large inductance more efficiently.

[0007] The present disclosure has been made in view of the above circumstances, and has an object to provide a spin inductor that efficiently exhibits large inductance.

[0008] To solve the above problems, the present disclosure provides the following means.

[0009] (1) A spin inductor according to a first aspect comprises a wiring layer, a first ferromagnetic layer in contact with a first surface of the wiring layer, and a second ferromagnetic layer in contact with a second surface of the wiring layer opposite the first surface.

[0010] (2) In the spin inductor according to the above aspect, the magnetization of the first ferromagnetic layer may be oriented in the opposite direction to the magnetization of the second ferromagnetic layer.

[0011] (3) The spin inductor according to the above aspect may further include a third ferromagnetic layer and a magnetic coupling layer, the magnetic coupling layer being located between the second ferromagnetic layer and the third ferromagnetic layer.

[0012] (4) In the spin inductor according to the above aspect, the magnetization of the first ferromagnetic layer may be oriented in the same direction as the magnetization of the third ferromagnetic layer.

[0013] (5) In the spin inductor according to the above aspect, the third ferromagnetic layer may have a thickness greater than that of the second ferromagnetic layer.

[0014] (6) In the spin inductor according to the above aspect, the wiring layer may have a laminated structure in which a first layer and a second layer are laminated.

[0015] (7) In the spin inductor according to the above aspect, the sign of the spin current generated in the first layer may be different from the sign of the spin current generated in the second layer.

[0016] (8) In the spin inductor according to the above aspect, the magnetization of the first ferromagnetic layer may be oriented in the same direction as the magnetization of the second ferromagnetic layer.

[0017] (9) The spin inductor according to the above aspect may further include a magnetic shield layer, the magnetic shield layer being spaced apart from the first ferromagnetic layer and the second ferromagnetic layer in the stacking direction.

[0018] (10) In the spin inductor according to the above aspect, the wiring layer may be configured so that spins can be injected into the first ferromagnetic layer and the second ferromagnetic layer, and the magnetizations of the first ferromagnetic layer and the second ferromagnetic layer may be configured so that precession can occur due to the injected spins.

[0019] 1 is a perspective view of a spin inductor according to a first embodiment; 2 is a cross-sectional view of a spin inductor according to the first embodiment; 3 is a plan view of a spin inductor according to the first embodiment; 4 is a schematic view for explaining a function of a spin inductor according to the first embodiment; 5 is a view for explaining a manufacturing method of a spin inductor according to the first embodiment; 6 is a view for explaining a manufacturing method of a spin inductor according to the first embodiment; 7 is a cross-sectional view of a spin inductor according to a second embodiment; 8 is a cross-sectional view of a spin inductor according to a third embodiment; 9 is a schematic view for explaining a function of a spin inductor according to the third embodiment; 10 is a perspective view of a spin inductor according to a fourth embodiment; 11 is a cross-sectional view of a spin inductor according to the fourth embodiment; 12 is a plan view of a spin inductor according to the fourth embodiment; 13 is an example of application of the spin inductor according to the present embodiment;

[0020] The present embodiment will be described in detail below with reference to the accompanying drawings. The drawings used in the following description may show characteristic portions enlarged for ease of understanding, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present disclosure is not limited thereto. Appropriate modifications can be made within the scope of the present disclosure.

[0021] First, let us define the directions. The direction in which each layer extends is defined as the x-direction, and the direction perpendicular to the x-direction is defined as the y-direction. For example, the first direction connecting the first terminal 20 and the second terminal 30 is defined as the x-direction. The second direction perpendicular to the first direction is defined as the y-direction, for example. The thickness direction of each layer is defined as the z-direction. The z-direction is perpendicular to the x-direction and y-directions.

[0022] "First Embodiment" Fig. 1 is a perspective view of a spin inductor 100 according to a first embodiment. Fig. 2 is a cross-sectional view of the spin inductor 100 according to the first embodiment. Fig. 3 is a plan view of the spin inductor 100 according to the first embodiment.

[0023] The spin inductor 100 is an inductor that operates by the vibration of magnetization in a magnetic material. The spin inductor 100 cuts the high-frequency component of a current and passes the constant component of the current. The current flows between a first terminal 20 and a second terminal 30. The spin inductor 100 is disposed in a portion where it is desired to cut off the high-frequency current. The high-frequency current is cut by the spin inductor 100, but a direct current flows through the spin inductor 100. For a direct current, the spin inductor 100 is a resistor.

[0024] The spin inductor 100 has a laminate 10 , a first terminal 20 and a second terminal 30 .

[0025] The first terminal 20 is in contact with the first side surface 10A of the laminate 10. The first terminal 20 is in contact with the wiring layer 1, the first ferromagnetic layer 2, and the second ferromagnetic layer 3 of the laminate 10. The first terminal 20 may also be in contact with the third ferromagnetic layer 5. The first side surface 10A is inclined with respect to the z direction. The first side surface 10A is inclined with respect to the yz plane.

[0026] The first terminal 20 is a conductor. Current flows from the first terminal 20 to the laminate 10. The laminate 10 is a laminate in which thin films are stacked. By tilting the first side surface 10A, the contact area between the thin films constituting the laminate 10 and the first terminal 20 becomes larger, and the electrical connection between the thin films constituting the laminate 10 and the first terminal 20 becomes stable.

[0027] The second terminal 30 contacts the second side surface 10B of the laminate 10. The second side surface 10B is a side surface different from the first side surface 10A of the laminate 10. The second side surface 10B is, for example, a side surface opposite the first side surface 10A in the x direction. The second terminal 30 contacts the wiring layer 1, the first ferromagnetic layer 2, and the second ferromagnetic layer 3 of the laminate 10. The second terminal 30 may also contact the third ferromagnetic layer 5. The second side surface 10B is inclined with respect to the z direction. The second side surface 10B is inclined with respect to the yz plane.

[0028] The second terminal 30 is a conductor. Current flows from the laminate 10 to the second terminal 30. The inclination of the second side surface 10B increases the contact area between the thin film constituting the laminate 10 and the second terminal 30, stabilizing the electrical connection between the thin film constituting the laminate 10 and the second terminal 30.

[0029] Here, an example has been shown in which the first terminal 20 and the second terminal 30 are formed on the side surfaces of the laminate 10, but the first terminal 20 and the second terminal 30 are not limited to this example. For example, the first terminal 20 and the second terminal 30 may be connected to the upper surface or the lower surface of the laminate 10. In this case, via wiring that contacts the laminate 10 and extends in the z direction becomes the first terminal 20 and the second terminal 30.

[0030] The stack 10 includes a wiring layer 1, a first ferromagnetic layer 2, a second ferromagnetic layer 3, a magnetic coupling layer 4, and a third ferromagnetic layer 5. The stack 10 may have a plurality of units each including a wiring layer 1, a first ferromagnetic layer 2, a second ferromagnetic layer 3, a magnetic coupling layer 4, and a third ferromagnetic layer 5. A spacer layer, for example, is sandwiched between adjacent units. The spacer layer may be a conductor, a semiconductor, or an insulator.

[0031] For example, the length of the wiring layer 1 in the x direction is shorter than the length of the y direction. For example, the length of the stack 10 in the x direction is shorter than the length of the stack 10 in the y direction. If the length of the wiring layer 1 in the y direction is long, the current density of the current flowing through the wiring layer 1 becomes small. Furthermore, if the length of the wiring layer 1 in the x direction is short, the resistance of the spin inductor 100 becomes low.

[0032] The wiring layer 1 includes any of a metal, alloy, intermetallic compound, metal boride, metal carbide, metal silicide, and metal phosphide, which have the function of generating a spin current by the spin Hall effect when a current flows. The wiring layer 1 is sometimes called a spin-orbit torque wiring.

[0033] The wiring layer 1 contains, for example, a non-magnetic heavy metal as a main component. Heavy metal means a metal having a specific gravity equal to or greater than that of yttrium (Y). Non-magnetic heavy metals are, for example, non-magnetic metals with a large atomic number of 39 or greater that have d electrons or f electrons in their outermost shells. The wiring layer 1 is made of, for example, Hf, Ta, or W. Non-magnetic heavy metals have stronger spin-orbit interactions than other metals. The spin-Hall effect is caused by the spin-orbit interaction. When spins tend to be unevenly distributed in the wiring layer 1 due to the spin-Hall effect, a spin current J Ｓ is more likely to occur.

[0034] The wiring layer 1 may also contain a magnetic metal. The magnetic metal is a ferromagnetic metal or an antiferromagnetic metal. A trace amount of magnetic metal contained in a non-magnetic material acts as a scattering factor for spins. A trace amount is, for example, 3% or less of the total molar ratio of the elements constituting the wiring layer. When spins are scattered by the magnetic metal, the spin-orbit interaction is enhanced, and the efficiency of generating a spin current relative to an electric current increases.

[0035] The wiring layer 1 may include a topological insulator. A topological insulator is a material whose interior is an insulator or a highly resistive material, but whose surface exhibits a spin-polarized metallic state. In topological insulators, an internal magnetic field is generated due to spin-orbit interaction. In topological insulators, new topological phases emerge due to the effect of spin-orbit interaction, even in the absence of an external magnetic field. Topological insulators can generate pure spin currents with high efficiency due to strong spin-orbit interaction and the breaking of inversion symmetry at the edges. Furthermore, because current flows only on the surface of topological insulators, high current densities can be achieved with a small amount of current.

[0036] Topological insulators include, for example, Sn, SnTe, and Bi. １．５ Sb ０．５ Te １．７ Se １．３ , TlBiSe ２ , Bi ２ Te ３ , Bi １－ｘ Sb ｘ , (Bi １－ｘ Sb ｘ ) ２ Te ３ Topological insulators are capable of generating spin currents with high efficiency.

[0037] The first ferromagnetic layer 2 contacts the first surface 1A of the wiring layer 1. The first ferromagnetic layer 2 contacts, for example, the bottom surface of the wiring layer 1.

[0038] The first ferromagnetic layer 2 is a ferromagnetic material, such as a metal selected from the group consisting of Cr, Mn, Co, Fe, and Ni, an alloy containing one or more of these metals, or an alloy containing one or more of these metals and at least one of B, C, and N.

[0039] Examples of the ferromagnetic material include Co—Fe, Co—Fe—B, Ni—Fe, Co—Ho alloy, Sm—Fe alloy, Fe—Pt alloy, Co—Pt alloy, and CoCrPt alloy. ０ CoFe alloys of this type have large saturation magnetization and strong magnetic anisotropy, and when used for the first ferromagnetic layer 2, the resonant frequency of the spin inductor 100 becomes high.

[0040] The first ferromagnetic layer 2 may also be a magnetic insulator. When the first ferromagnetic layer 2 is a magnetic insulator, it is particularly preferable that the wiring layer 1 is a topological insulator. Since current flows only at the junction between the magnetic insulator and the topological insulator, current loss can be reduced, and energy loss due to heat generation, etc. can be reduced.

[0041] The first ferromagnetic layer 2 may also be a ferrimagnetic insulator or an antiferromagnetic insulator. When the first ferromagnetic layer 2 is an antiferromagnetic insulator, it is particularly preferable that the wiring layer 1 is a topological insulator. Since current flows only at the junction surface between the antiferromagnetic insulator and the topological insulator, current loss can be suppressed, and energy loss due to heat generation, etc. can be suppressed. Furthermore, when the first ferromagnetic layer 2 is an antiferromagnetic insulator, the resonant frequency of the first ferromagnetic layer 2 becomes high, and resonance does not occur even in the high frequency range of 10 GHz or more. Therefore, a spin inductor in which the first ferromagnetic layer 2 is an antiferromagnetic insulator can exhibit stable inductance over a wide frequency band. For example, antiferromagnetic insulators can be made of NiO, MnO, Cr ２ O ３ , oxides containing magnetic elements such as ferrite and garnet, sulfides containing magnetic elements such as MnS, FeCl ２ These include chlorides containing magnetic elements such as:

[0042] The second ferromagnetic layer 3 contacts the second surface 1B of the wiring layer 1. The second surface 1B is the surface of the wiring layer 1 that faces the first surface 1A. The second ferromagnetic layer 3 covers, for example, the entire upper surface of the wiring layer 1.

[0043] The second ferromagnetic layer 3 includes the same material as the first ferromagnetic layer 2. The second ferromagnetic layer 3 may include the same material as the first ferromagnetic layer 2, or may include a different material.

[0044] The magnetization M2 of the first ferromagnetic layer 2 and the magnetization M3 of the second ferromagnetic layer 3 are oriented in opposite directions when no current flows through the wiring layer 1 and no external magnetic field is applied (hereinafter referred to as the initial state). Here, "no current flows" refers to a state in which no potential difference is applied to the wiring layer 1. Furthermore, "no external magnetic field is applied" refers to a state in which no intentional magnetic field is applied to the first ferromagnetic layer 2 or the second ferromagnetic layer 3. In the initial state, the magnetization M2 of the first ferromagnetic layer 2 is oriented in the opposite direction to the magnetization M3 of the second ferromagnetic layer 3. In the example shown in FIG. 2, the magnetization M2 is oriented in the -z direction and the magnetization M3 is oriented in the +z direction, but these relationships may be reversed. Furthermore, the magnetization M2 and the magnetization M3 may be oriented in any direction within the xy plane or in a direction tilted from the xy plane toward the z direction.

[0045] The magnetic coupling layer 4 is, for example, located between the second ferromagnetic layer 3 and the third ferromagnetic layer 5. The magnetic coupling layer 4 is a layer that does not inhibit the magnetic coupling between the second ferromagnetic layer 3 and the third ferromagnetic layer 5.

[0046] The magnetic coupling layer 4 includes at least one selected from the group consisting of, for example, Ru, Ir, and Rh. The magnetic coupling layer 4 is, for example, a metal film of Ru, Ir, or Rh.

[0047] For example, the second ferromagnetic layer 3 and the third ferromagnetic layer 5 are antiferromagnetically coupled with the magnetic coupling layer 4 sandwiched therebetween. In this case, the second ferromagnetic layer 3, the magnetic coupling layer 4, and the third ferromagnetic layer 5 form a synthetic antiferromagnetic structure (SAF structure). The antiferromagnetic coupling between the second ferromagnetic layer 3 and the third ferromagnetic layer 5 increases the coercive force of the second ferromagnetic layer 3 compared to a case where the third ferromagnetic layer 5 is not provided, and a coercive force difference can be generated between the first ferromagnetic layer 2 and the second ferromagnetic layer 3.

[0048] The second ferromagnetic layer 3 and the third ferromagnetic layer 5 may be ferromagnetically coupled with a magnetic coupling layer 4 sandwiched therebetween.

[0049] The third ferromagnetic layer 5 is located opposite the second ferromagnetic layer 3 with the magnetic coupling layer 4 sandwiched therebetween. The third ferromagnetic layer 5 contains the same material as the first ferromagnetic layer 2. The third ferromagnetic layer 5 may contain the same material as the first ferromagnetic layer 2, or may contain a different material.

[0050] In the initial state, the magnetization M5 of the third ferromagnetic layer 5 is oriented in the same direction as the magnetization M2 of the first ferromagnetic layer 2. In addition, in the initial state, the magnetization M5 of the third ferromagnetic layer 5 is oriented in the opposite direction to the magnetization M3 of the second ferromagnetic layer 3. In the example shown in Figure 2, the magnetization M5 is oriented in the -z direction, but the magnetization M5 may also be oriented in the +z direction, in any direction within the xy plane, or in a direction tilted from the xy plane toward the z direction.

[0051] The thickness of the third ferromagnetic layer 5 in the z direction is, for example, thicker than the thickness of the second ferromagnetic layer 3. By making the thickness of the third ferromagnetic layer 5 thicker than the thickness of the second ferromagnetic layer 3, it becomes easier to make the magnetization of the first ferromagnetic layer 2 and the magnetization of the second ferromagnetic layer 3 oriented in opposite directions when manufacturing the spin inductor 100.

[0052] Next, a description will be given of the function of the spin inductor 100. FIG.

[0053] The spin inductor 100 functions as an inductor when a current flows along the wiring layer 1. When a current is applied between the first terminal 20 and the second terminal 30, the current flows within the plane of the wiring layer 1.

[0054] The current flowing in the wiring layer 1 generates a spin current due to the spin Hall effect.

[0055] The spin Hall effect is a phenomenon in which, when an electric current is passed through it, a spin current is induced in a direction perpendicular to the direction of the current flow (for example, the z direction) due to spin-orbit interaction. The spin Hall effect is similar to the standard Hall effect in that the direction of movement of moving charges (electrons) is bent. In the standard Hall effect, the direction of movement of charged particles moving in a magnetic field is bent by the Lorentz force. In contrast, in the spin Hall effect, the direction of spin movement is bent simply by the movement of electrons (the flow of electric current), even in the absence of a magnetic field.

[0056] For example, when a current flows in the x direction of the wiring layer 1, the spins S1 polarized in the -y direction are bent in the +z direction relative to the direction of travel, and the spins S2 polarized in the +y direction are bent in the -z direction relative to the direction of travel.

[0057] The spins S2 are injected from the first surface 1A into the adjacent second ferromagnetic layer 3. The spins S1 are injected from the second surface 1B into the adjacent first ferromagnetic layer 2. When the distance between the wiring layer 1 and the first ferromagnetic layer 2 is equal to or shorter than the spin diffusion length of the spins S2, the spins S2 generated in the wiring layer 1 can be efficiently injected into the first ferromagnetic layer 2. Furthermore, when the distance between the wiring layer 1 and the second ferromagnetic layer 3 is equal to or shorter than the spin diffusion length of the spins S1, the spins S1 generated in the wiring layer 1 can be efficiently injected into the second ferromagnetic layer 3.

[0058] The magnetization M2 of the first ferromagnetic layer 2 precesses due to the spins S2 injected from the wiring layer 1. The coercive force of the magnetization M2 and the magnitude of the current flowing through the wiring layer 1 are adjusted so that the magnetization M2 precesses without being reversed due to the injected spins S2.

[0059] The magnetization M3 of the second ferromagnetic layer 3 precesses due to the spins S1 injected from the wiring layer 1. The coercive force of the magnetization M3 and the magnitude of the current flowing through the wiring layer 1 are adjusted so that the magnetization M3 precesses without being reversed by the injected spins S1.

[0060] When the magnetization M2 of the first ferromagnetic layer 2 and the magnetization M3 of the second ferromagnetic layer 3 precess, energy conversion occurs between the magnetic moment and current, and the spin inductor 100 exhibits an inductor function. When the first ferromagnetic layer 2 and the second ferromagnetic layer 3 are magnetic insulators, localized spins contained in the magnetic insulator precess, and energy conversion occurs between the spin waves propagating from the vibrations of the spins and the current, and the spin inductor 100 exhibits an inductor function.

[0061] From the viewpoint of maintaining the precession of magnetization M2 and magnetization M3, magnetization M2 and magnetization M3 preferably have a component oriented in the z direction in the initial state, and are more preferably oriented in the z direction. When magnetization M2 and magnetization M3 are oriented in the x direction or y direction, magnetization reversal may occur even when no external magnetic field is applied, and the precession of magnetization may not be maintained. When magnetization M2 and magnetization M3 are oriented in the z direction, magnetization reversal is unlikely to occur in the absence of a magnetic field. Because the spin inductor 100 exhibits its inductor function by utilizing energy conversion between a magnetic moment and a current, the inductor function is not fully exhibited when the precession of magnetization stops.

[0062] Even if the magnetization M2 and the magnetization M3 are oriented in the x-direction or the y-direction, it is possible to maintain the precession of the magnetization by adjusting the density of the current flowing through the wiring layer 1.

[0063] Because the spin inductor 100 generates a resonance phenomenon at the ferromagnetic resonance frequency of the first ferromagnetic layer 2 and the second ferromagnetic layer 3, stable operation as an inductor is difficult near the resonance frequency. Therefore, the spin inductor 100 is used at a frequency sufficiently lower or sufficiently higher than the ferromagnetic resonance frequency of the spin inductor 100. This sufficiently low or sufficiently high frequency generally indicates a frequency that is deviated from the ferromagnetic resonance frequency by 5% or more, with the ferromagnetic resonance frequency as the reference. The spin inductor 100 can generate inductance even at frequencies exceeding 10 GHz or THz, for example. Furthermore, the inductance generated by the spin inductor 100 functions satisfactorily even at 1 nH or less.

[0064] Furthermore, the magnetization M5 of the third ferromagnetic layer 5, which is antiferromagnetically coupled with the second ferromagnetic layer 3, may precess together with the magnetization M3 of the second ferromagnetic layer 3. When the magnetization M5 of the third ferromagnetic layer 5 precesses, the spin inductor 100 exhibits a larger inductance. Furthermore, when the period of precession of the magnetization M5 of the third ferromagnetic layer 5 differs from the period of precession of the magnetization M2 of the first ferromagnetic layer 2 and the magnetization M3 of the second ferromagnetic layer 3, the spin inductor 100 exhibits an inductor function for high-frequency currents in a wider band.

[0065] Next, a method for manufacturing the spin inductor 100 according to this embodiment will be described. Figures 5 to 7 are schematic diagrams for explaining the method for manufacturing the spin inductor according to this embodiment.

[0066] 5, a ferromagnetic layer 92, a conductive layer 91, a ferromagnetic layer 93, an intermediate layer 94, and a ferromagnetic layer 95 are stacked in this order. The layers can be stacked by, for example, sputtering, chemical vapor deposition (CVD), electron beam evaporation (EB evaporation), atomic laser deposition, or the like.

[0067] Next, as shown in Fig. 6, the stack is processed into a predetermined shape. Each layer can be processed using, for example, photolithography. Through this processing, the ferromagnetic layer 92 becomes the first ferromagnetic layer 2, the conductive layer 91 becomes the wiring layer 1, the ferromagnetic layer 93 becomes the second ferromagnetic layer 3, the intermediate layer 94 becomes the magnetic coupling layer 4, and the ferromagnetic layer 95 becomes the third ferromagnetic layer 5.

[0068] 6, an external magnetic field E is applied to the stack. The external magnetic field E may be applied after or before processing the stack. The strength of the external magnetic field E is set to be such that the magnetization of each layer is sufficiently oriented in the direction of the applied magnetic field. The magnetization M2 of the first ferromagnetic layer 2, the magnetization M3 of the second ferromagnetic layer 3, and the magnetization M5 of the third ferromagnetic layer 5 are oriented in the direction in which the external magnetic field E is applied.

[0069] 7, the application of the external magnetic field E to the stack is stopped. The second ferromagnetic layer 3 is antiferromagnetically coupled to the third ferromagnetic layer 5 with the magnetic coupling layer 4 sandwiched therebetween. Therefore, the magnetization M3 of the second ferromagnetic layer 3, which has a smaller coercive force than the third ferromagnetic layer 5, is reversed when the application of the external magnetic field E is stopped. The magnetization M3 of the second ferromagnetic layer 3 becomes antiparallel to the magnetization M5 of the third ferromagnetic layer 5.

[0070] Next, a conductive layer is applied so as to cover the laminate 10 fabricated in Fig. 7. Then, the central portion of the conductive layer in the x direction is removed to form the first terminal 20 and the second terminal 30. By this procedure, the spin inductor 100 according to this embodiment can be fabricated.

[0071] As described above, in the spin inductor 100 according to this embodiment, the magnetization M2 of the first ferromagnetic layer 2 and the magnetization M3 of the second ferromagnetic layer 3 precess due to spins injected from the wiring layer 1. Energy conversion occurs between the magnetic moments of the precessing magnetizations M2 and M3 and current, causing the spin inductor 100 to function as an inductor. Furthermore, the spin inductor according to this embodiment utilizes spins generated from both sides of the wiring layer 1, and therefore exhibits a larger inductance than when only spins generated from one side are used.

[0072] Furthermore, the spin inductor according to this embodiment exhibits inductor function by utilizing energy conversion between current and magnetic moment, and therefore can exhibit strong inductance even in a small size. For example, even if the maximum width of the laminate 10 when viewed in a planar view from the z direction is 0.003 mm or less, it can exhibit an inductance of 0.1 μH to 10 μH. Small inductance elements are particularly desired in areas where it is difficult to incorporate large elements, such as space and cryogenic temperatures. Furthermore, even if the maximum width of the spin inductor 10 when viewed in a planar view from the z direction is several tens of nanometers and the length is several hundred nanometers, the spin inductor 100 exhibits an inductance of several nH to several hundred nH.

[0073] 8 is a cross-sectional view of a spin inductor 101 according to a second embodiment. In the spin inductor 101 according to the second embodiment, the same components as those in the spin inductor 100 according to the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0074] The spin inductor 101 according to the second embodiment includes a stack 11, a first terminal 20, and a second terminal 30. The stack 11 includes a wiring layer 1, a first ferromagnetic layer 2, and a second ferromagnetic layer 3. The stack 11 differs from the stack 10 in that it does not include a magnetic coupling layer 4 or a third ferromagnetic layer 5.

[0075] The spin inductor 101 according to the second embodiment can be fabricated by the same procedure as the spin inductor 100 according to the first embodiment. The magnetization directions of the magnetization M2 and the magnetization M3 can be controlled by utilizing the difference in coercivity between the second ferromagnetic layer 3 and the third ferromagnetic layer 5. For example, after applying an external magnetic field in a first direction, the magnetization directions of the magnetization M2 and the magnetization M3 can be controlled by applying an external magnetic field in a second direction opposite to the first direction, with a strength that reverses the magnetization of only one of the second ferromagnetic layer 3 and the third ferromagnetic layer 5.

[0076] The spin inductor 101 according to the second embodiment utilizes spins generated from both sides of the wiring layer 1, and therefore exhibits a larger inductance than when only spins generated from one side are utilized.

[0077] 9 is a cross-sectional view of a spin inductor 102 according to a third embodiment. In the spin inductor 102 according to the third embodiment, the same components as those in the spin inductor 100 according to the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0078] The spin inductor 102 according to the third embodiment includes a stack 12, a first terminal 20, and a second terminal 30. The stack 12 includes a wiring layer 6, a first ferromagnetic layer 2, and a second ferromagnetic layer 3. The stack 12 differs from the stack 10 in that it does not include a magnetic coupling layer 4 or a third ferromagnetic layer 5, and has a different configuration for the wiring layer 6. In the initial state of the stack 12, the magnetization M2 of the first ferromagnetic layer 2 and the magnetization M3 of the second ferromagnetic layer 3 are oriented in the same direction.

[0079] The wiring layer 6 has a laminated structure in which a first layer 7 and a second layer 8 are laminated. The first layer 7 is in contact with the first ferromagnetic layer 2. The second layer 8 is in contact with the second ferromagnetic layer 3. The wiring layer 6 may further include layers other than the first layer 7 and the second layer 8.

[0080] The first layer 7 and the second layer 8 each contain one of a metal, alloy, intermetallic compound, metal boride, metal carbide, metal silicide, and metal phosphide, which have the function of generating a spin current by the spin Hall effect when a current flows. The first layer 7 and the second layer 8 can be made of the same material as the wiring layer 1.

[0081] The first layer 7 injects spins generated in the first layer 7 by the spin Hall effect into the first ferromagnetic layer 2. The second layer 8 injects spins generated in the second layer 8 by the spin Hall effect into the second ferromagnetic layer 3. The signs of the spin currents generated in the first layer 7 and the second layer 8 are, for example, different.

[0082] The sign of the spin current indicates on which surface spins polarized in which direction are accumulated when a current flows in the x direction of the wiring layer 6. For example, if the sign of the spin current is "positive" when spins S1 polarized in the -y direction accumulate on the first surface and spins S2 polarized in the +y direction accumulate on the second surface, the sign of the spin current is "negative" when spins S1 polarized in the +y direction accumulate on the first surface and spins S2 polarized in the -y direction accumulate on the second surface.

[0083] For example, the first layer 7 and the second layer 8 have different polarities of the spin Hall angle. When the "polarity of the spin Hall angle" is different, the first spin S1 bends in the z direction or the -z direction, resulting in different signs of the spin current. The polarities of the spin Hall angle of the first layer 7 and the second layer 8 can be changed by selecting the materials constituting the first layer 7 and the second layer 8. For example, when a layer mainly contains a metal element belonging to any of groups 8, 9, 10, 11, and 12, the spin Hall angle of that layer often exhibits a positive polarity. Furthermore, when a layer mainly contains a metal element belonging to any of groups 3, 4, 5, and 6, the spin Hall angle of that layer often exhibits a negative polarity. The polarity of the spin Hall angle is not determined solely by the material constituting the layer, but is also affected by factors such as the layer thickness.

[0084] Next, a description will be given of the function of the spin inductor 102. FIG.

[0085] The spin inductor 102 functions as an inductor when a current flows along the wiring layer 6. When a current is applied between the first terminal 20 and the second terminal 30, the current flows within the plane of the wiring layer 6.

[0086] The wiring layer 6 includes a first layer 7 and a second layer 8. A current flows in the x direction inside each of the first layer 7 and the second layer 8. The current flowing inside the first layer 7 and the second layer 8 generates a spin current due to the spin Hall effect.

[0087] The signs of the spin currents generated inside the first layer 7 and the second layer 8 are different. In the first layer 7, the spins S1 polarized in the -y direction are bent in the -z direction relative to the direction of travel, and the spins S2 polarized in the +y direction are bent in the +z direction relative to the direction of travel. In contrast, in the second layer 8, the spins S1 polarized in the -y direction are bent in the +z direction relative to the direction of travel, and the spins S2 polarized in the +y direction are bent in the -z direction relative to the direction of travel.

[0088] The spins S1 accumulated in the first surface 7A are injected from the first surface 7A into the adjacent first ferromagnetic layer 2. The spins S1 accumulated in the second surface 8B are injected from the second surface 8B into the adjacent second ferromagnetic layer 3. Spins S1 polarized in the same direction are injected into the first ferromagnetic layer 2 and the second ferromagnetic layer 3. Therefore, in the initial state, it is preferable that the magnetization M2 of the first ferromagnetic layer 2 and the magnetization M3 of the second ferromagnetic layer 3 are oriented in the same direction.

[0089] By setting the distance between the first layer 7 and the first ferromagnetic layer 2 to be equal to or shorter than the spin diffusion length of the spins S1, the spins S1 generated in the first layer 7 can be efficiently injected into the first ferromagnetic layer 2. Furthermore, by setting the distance between the second layer 8 and the second ferromagnetic layer 3 to be equal to or shorter than the spin diffusion length of the spins S1, the spins S1 generated in the second layer 8 can be efficiently injected into the second ferromagnetic layer 3.

[0090] The magnetization M2 of the first ferromagnetic layer 2 precesses due to the spins S1 injected from the first layer 7. The coercive force of the magnetization M2 and the magnitude of the current flowing through the wiring layer 6 are adjusted so that the magnetization M2 precesses without being reversed by the injected spins S1.

[0091] The magnetization M3 of the second ferromagnetic layer 3 precesses due to the spins S1 injected from the second layer 8. The coercive force of the magnetization M3 and the magnitude of the current flowing through the wiring layer 6 are adjusted so that the magnetization M3 precesses without being reversed by the injected spins S1.

[0092] When the magnetization M2 of the first ferromagnetic layer 2 and the magnetization M3 of the second ferromagnetic layer 3 precess, energy conversion occurs between the magnetic moment and the current, and the spin inductor 102 exhibits an inductor function.

[0093] As described above, the spin inductor 102 according to the third embodiment utilizes spins injected from both sides of the wiring layer 6 into the adjacent ferromagnetic layers, and therefore exhibits a large inductance.

[0094] Although an example has been shown in which, in the initial state, the magnetization M2 of the first ferromagnetic layer 2 and the magnetization M3 of the second ferromagnetic layer 3 are oriented in the same direction and the signs of the spin currents generated in the first layer 7 and the second layer 8 are different, the configuration of the stack 12 is not limited to this example. For example, in the initial state, the magnetization M2 of the first ferromagnetic layer 2 and the magnetization M3 of the second ferromagnetic layer 3 may be oriented in opposite directions and the signs of the spin currents generated in the first layer 7 and the second layer 8 may be the same.

[0095] "Fourth Embodiment" Fig. 11 is a perspective view of a spin inductor 103 according to a fourth embodiment. Fig. 12 is a cross-sectional view of the spin inductor 103 according to the fourth embodiment. Fig. 13 is a plan view of the spin inductor 103 according to the fourth embodiment. In the spin inductor 103 according to the fourth embodiment, the same components as those in the spin inductor 100 according to the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0096] The spin inductor 103 has a stack 10, a first terminal 20, a second terminal 30, a magnetic shield 40, an insulating layer 51, and an insulating layer 52. The spin inductor 103 differs from the spin inductor 100 in that it has the magnetic shield 40.

[0097] The magnetic shield 40 includes, for example, a first yoke 41 , a second yoke 42 , and a via 43 .

[0098] The first yoke 41 is spaced apart from the stack 10 in the z direction. The first yoke 41 is spaced apart from the first ferromagnetic layer 2, the second ferromagnetic layer 3, and the third ferromagnetic layer 5 in the z direction.

[0099] Between the laminate 10 and the first yoke 41, for example, there is an insulating layer 51. The insulating layer 51 is an insulating layer that insulates the laminate 10 from the magnetic shield 40. The insulating layer 51 is made of, for example, silicon oxide (SiO ｘ ), silicon nitride (SiN ｘ ), silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al ２ O ３ ), zirconium oxide (ZrO ｘ ), magnesium oxide (MgO), aluminum nitride (AlN), etc.

[0100] The second yoke 42 is spaced apart from the laminate 10 in the z direction. The first yoke 41 and the second yoke 42 sandwich the laminate 10 in the z direction.

[0101] Between the laminate 10 and the second yoke 42, for example, there is an insulating layer 52. The insulating layer 52 is an insulating layer that insulates the laminate 10 from the magnetic shield 40. The insulating layer 52 includes the same material as the insulating layer 51.

[0102] The first yoke 41 and the second yoke 42 suppress the influence of an external magnetic field on the stack 10. The first yoke 41 and the second yoke 42 also facilitate orienting the magnetization of the first ferromagnetic layer 2, the second ferromagnetic layer 3, and the third ferromagnetic layer 5 in the z direction. When the magnetization is strongly oriented in the z direction, the axes of the precession of the magnetization M2 and the magnetization M3 become stable, and the spin inductor 103 exhibits a large inductance.

[0103] The via 43 connects the first yoke 41 and the second yoke 42. When the first yoke 41 and the second yoke 42 are connected by the via 43, magnetic flux returns along the magnetic shield 40. As a result, the magnetization M2 and the magnetization M3 are more strongly oriented in the z direction, and the spin inductor 103 exhibits a large inductance.

[0104] The spin inductor 103 according to the fourth embodiment has the same effects as the spin inductor 100 according to the first embodiment. Furthermore, the magnetic shield 40 can reduce the influence of an external magnetic field on the magnetization M2 and the magnetization M3. Furthermore, when the magnetic shield 40 is configured as described above, the precession of the magnetization M2 and the magnetization M3 is stabilized, and the spin inductor 103 exhibits a large inductance.

[0105] 11 to 13. For example, the magnetic shield 40 may include only the first yoke 41 or the second yoke 42. The magnetic shield 40 may also be applied to the spin inductors according to the second and third embodiments.

[0106] The first to fourth embodiments have been illustrated above, and specific configurations of spin inductors have been described. The spin inductor according to the present disclosure is not limited to these exemplary configurations, and various modifications are possible as long as the spirit of the invention is met. Furthermore, the spin inductor according to the present disclosure can be incorporated into a module for use, for example. Figure 14 shows an example of use of the spin inductor according to this embodiment.

[0107] In recent years, there has been a growing interest in integrating semiconductor circuits and devices with specific functions, such as memory, into a single chip. The technology for integrating semiconductor circuits and devices such as memory into a single chip is called "chiplet" or "heterointegration." Integrating these into a single chip reduces latency, power consumption, and costs. Even with these technologies, passive components must be separately placed around the chip for it to function. Therefore, even if the chip is highly integrated, passive components can become a challenge in miniaturizing the module. By incorporating passive components into chiplets and heterointegration, further miniaturization of modules is expected.

[0108] The chip C shown in FIG. 14 includes a semiconductor circuit L1, a connection layer L2, a wiring layer L3, a memory layer L4, a sensor layer L5, an LCR (passive component) layer L6, and an all-solid-state thin-film battery layer L7, which are stacked in this order. Although each layer is bonded to form a single chip, spacing is provided in FIG. 14 for ease of understanding. The spin inductor according to the present disclosure is formed, for example, in the LCR layer L6. The LCR layer L6 may form not only passive components such as conventional electronic components, such as inductance, capacitance, and resistance, but also spin inductors and spin-tunable capacitances. The LCR layer L6 is connected to other layers via contact vias, and the entire chip C is utilized as a single module. The spin inductor according to the present disclosure can be applied to devices that also include sensors and power sources, as shown in FIG. 14, and can autonomously collect information.

[0109] 1, 6...wiring layer, 1A...first surface, 1B...second surface, 2...first ferromagnetic layer, 3...second ferromagnetic layer, 4...magnetic coupling layer, 5...third ferromagnetic layer, 7...first layer, 8...second layer, 10, 11, 12...laminated body, 10A...first side surface, 10B...second side surface, 20...first terminal, 30...second terminal, 40...magnetic shield, 41...first yoke, 42...second yoke, 43...via, 51, 52...insulating layer, 91...conductive layer, 92, 93, 95...ferromagnetic layer, 94...intermediate layer, 100, 101, 102, 103...spin inductor, M2, M3, M5...magnetization

Claims

1. A spin inductor comprising: a wiring layer; a first ferromagnetic layer in contact with a first surface of the wiring layer; and a second ferromagnetic layer in contact with a second surface of the wiring layer opposite the first surface.

2. The spin inductor of claim 1, wherein the magnetization of the first ferromagnetic layer is oriented in the opposite direction to the magnetization of the second ferromagnetic layer.

3. The spin inductor of claim 1, further comprising a third ferromagnetic layer and a magnetic coupling layer, the magnetic coupling layer being between the second ferromagnetic layer and the third ferromagnetic layer.

4. The spin inductor according to claim 3, wherein the magnetization of the first ferromagnetic layer is oriented in the same direction as the magnetization of the third ferromagnetic layer.

5. The spin inductor according to claim 3, wherein the third ferromagnetic layer has a thickness greater than that of the second ferromagnetic layer.

6. The spin inductor according to claim 1, wherein the wiring layer has a first layer and a second layer.

7. A spin inductor according to claim 6, wherein the sign of the spin current generated in the first layer is different from the sign of the spin current generated in the second layer.

8. The spin inductor of claim 6, wherein the magnetization of the first ferromagnetic layer is oriented in the same direction as the magnetization of the second ferromagnetic layer.

9. The spin inductor according to claim 1, further comprising a magnetic shield layer, the magnetic shield layer being spaced apart from the first ferromagnetic layer and the second ferromagnetic layer in the stacking direction.

10. The spin inductor described in claim 1, wherein the wiring layer is configured so that spins can be injected into the first ferromagnetic layer and the second ferromagnetic layer, and the magnetizations of the first ferromagnetic layer and the second ferromagnetic layer are configured so that they can precess due to the injected spins.