Domain wall moving element and magnetic array

Abstract

To provide a highly reliable domain wall displacement element and magnetic array.SOLUTION: A domain wall moving element includes: a first ferromagnetic layer; a first magnetization fixed part; and a second magnetization fixed part. The first magnetization fixed part includes: a first magnetization fixed layer; a first nonmagnetic layer; and a second magnetization fixed layer having a first diffusion prevention structure. The second magnetization fixed part includes: a third magnetization fixed layer; a second nonmagnetic layer; and a fourth magnetization fixed layer. The fourth magnetization fixed layer includes: a second diffusion prevention structure; and a first region. The first region is located farther away from the second nonmagnetic layer than the second diffusion prevention structure. The first region includes a ferromagnetic element and a nonmagnetic element.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to domain wall motion elements and magnetic arrays. [Background technology]

[0002] Magnetoresistive effect elements are known that utilize a change in resistance value (magnetoresistance change) based on a change in the relative angle between the magnetizations of two ferromagnetic layers. For example, the domain wall motion type magnetoresistive effect element (hereinafter referred to as domain wall motion element) described in Patent Document 1 is an example of a magnetoresistive effect element. In domain wall motion elements, the resistance value in the stacking direction changes depending on the position of the domain wall, and data can be recorded in multi-value or analog form. Domain wall motion elements have high linearity and symmetry in the resistance change, excellent rewrite durability, and are capable of high-speed operation.

[0003] Patent Document 1 describes that magnetization fixed portions that limit the range of movement of the domain wall are provided at both ends of the magnetic recording layer. The two magnetization fixed portions have different magnetization orientation directions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 230877 Summary of the Invention [Problem to be solved by the invention]

[0005] It is not easy to orient the magnetizations of the two magnetization fixed parts in different directions.

[0006] The present disclosure has been made in view of the above problems, and has an object to provide a highly reliable domain wall motion element and magnetic array. [Means for solving the problem]

[0007] A domain wall motion element according to a first aspect includes a first ferromagnetic layer having a domain wall therein, a first magnetization fixed unit connected to the first ferromagnetic layer, and a second magnetization fixed unit connected to the first ferromagnetic layer at a position spaced apart from the first magnetization fixed unit. The first magnetization fixed unit includes a first magnetization fixed layer, a first non-magnetic layer, and a second magnetization fixed layer. The first magnetization fixed layer and the second magnetization fixed layer are antiferromagnetically coupled with the first non-magnetic layer sandwiched therebetween. The first magnetization fixed layer is in contact with the first ferromagnetic layer. The first non-magnetic layer is located between the first magnetization fixed layer and the second magnetization fixed layer in the stacking direction. The second magnetization fixed layer has a first diffusion prevention structure. The second magnetization fixed unit includes a third magnetization fixed layer, a second non-magnetic layer, and a fourth magnetization fixed layer. The third magnetic pinned layer and the fourth magnetic pinned layer are antiferromagnetically coupled with the second nonmagnetic layer sandwiched therebetween. The third magnetic pinned layer is in contact with the first ferromagnetic layer. The second nonmagnetic layer is located between the third magnetic pinned layer and the fourth magnetic pinned layer in the stacking direction. The fourth magnetic pinned layer has a second diffusion prevention structure and a first region. The first region is located farther from the second nonmagnetic layer than the second diffusion prevention structure. The first region includes a ferromagnetic element and a nonmagnetic element. [Effects of the Invention]

[0008] A highly reliable domain wall motion element and magnetic array can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram of a magnetic array according to a first embodiment. [Figure 2] FIG. 2 is a circuit diagram of an integrated region of the magnetic array according to the first embodiment. [Figure 3] FIG. 2 is a cross-sectional view of the vicinity of a domain wall motion element of the magnetic array according to the first embodiment. [Figure 4] 1 is a cross-sectional view of a domain wall motion element according to a first embodiment. [Figure 5] FIG. 1 is a plan view of a domain wall motion element according to a first embodiment. [Figure 6]FIG. 2 is a cross-sectional view of a first magnetization fixed unit according to the first embodiment. [Figure 7] FIG. 3 is a cross-sectional view of a second magnetization fixed unit according to the first embodiment. [Figure 8] FIG. 1 is a conceptual diagram of a neural network. [Figure 9] FIG. 1 is a block diagram showing a system including a neuromorphic device according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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 the sake of clarity, and the dimensional ratios of the components may differ from the actual values. The materials, dimensions, and the like exemplified in the following description are merely examples, and the present embodiment is not limited thereto. Appropriate modifications can be made within the scope of the effects of the present embodiment.

[0011] First, the directions are defined. The x and y directions are directions substantially parallel to one surface of the substrate Sub (see FIG. 3), which will be described later. The x direction is the direction in which the first ferromagnetic layer, which will be described later, extends. The y direction is a direction perpendicular to the x direction. The z direction is the direction from the substrate, which will be described later, to the domain wall motion element. The z direction is an example of a stacking direction. In this specification, the +z direction may be expressed as "up" and the -z direction as "down," but these expressions are for convenience and do not define the direction of gravity. Furthermore, in this specification, "extending in the x direction" means, for example, that the dimension in the x direction is larger than the smallest dimension among the dimensions in the x, y, and z directions. The same applies to extending in other directions.

[0012] [First embodiment] 1 is a block diagram of a magnetic array MA according to a first embodiment. The magnetic array MA has an integration region 1 and a peripheral region 2. The magnetic array MA can be used, for example, in a magnetic memory, a multiply-and-accumulate unit, a neuromorphic device, a spin memristor, or a magneto-optical element.

[0013] The accumulation region 1 is a region where multiple domain wall motion elements are accumulated. When the magnetic array MA is used as a memory, data is stored in the accumulation region 1. When the magnetic array MA is used as a neuromorphic device, learning and inference are performed in the accumulation region 1.

[0014] The peripheral region 2 is a region where a control element that controls the operation of the domain wall motion element in the integration region 1 is mounted. The peripheral region 2 includes, for example, a control device 3, a resistance detection device 4, and an output section 5.

[0015] The control device 3 is configured to be able to apply a pulse to at least one of the plurality of domain wall motion elements in the accumulation region 1. The control device 3 includes, for example, a control unit 6 and a power supply 7.

[0016] The control unit 6 has, for example, a processor and a memory. The processor is, for example, a CPU (Central Processing Unit). The processor operates based on an operating program stored in the memory. The control unit 6 controls, for example, the address of the domain wall motion element to which the pulse is applied, the magnitude of the pulse (voltage, pulse length) to be applied to a specific domain wall motion element, etc. The control unit 6 may also have a clock, a counter, a random number generator, etc. The clock serves as an index for the timing of applying the pulse, and the counter counts the number of times the pulse is applied, etc. The power supply 7 applies pulses to the domain wall motion element according to instructions from the control unit 6.

[0017] The resistance detection device 4 is configured to detect the resistance value of the domain wall motion element in the integration region 1. The resistance detection device 4 may detect the resistance of each domain wall motion element in the integration region 1, or may detect the total resistance of domain wall motion elements belonging to the same column, for example. The resistance detection device 4 may, for example, detect the value of a current flowing through a reference resistor, or may detect the charge after temporarily storing the output as a charge in a capacitor. The resistance detection device 4 may, for example, have a comparator that compares the magnitude of the detected resistance value. The comparator may, for example, compare the detected resistance value with another detected resistance value, or may compare the detected resistance value with a preset reference resistance value.

[0018] The output unit 5 is connected to the resistance detection device 4. The output unit 5 includes, for example, a processor, an output capacitor, an amplifier, a converter, etc. When the magnetic array MA is used as a neuromorphic device, the output unit 5 may perform a calculation to substitute the detection result of the resistance detection device 4 into an activation function. The calculation is performed, for example, by a processor. The output unit 5 outputs the calculation result to the outside. When the magnetic array MA is used as a neuromorphic device, for example, the calculation result may be output as an input signal for another magnetic array, or may be output as a discrimination rate to the outside. The output unit 5 may also feed back the calculation result to the control device 3.

[0019] 2 is a circuit diagram of the integrated region 1 according to the first embodiment. The integrated region 1 includes a plurality of domain wall motion elements 100, a plurality of write lines WL, a plurality of common lines CL, a plurality of read lines RL, a plurality of first switches SW1, and a plurality of second switches SW2. The third switch SW3 may belong to the control device 3 in the peripheral region 2, for example.

[0020] The plurality of domain wall motion elements 100 are arranged, for example, in a matrix. The plurality of domain wall motion elements 100 are not limited to those in which actual elements are arranged in a matrix, but may be those in which actual elements are arranged three-dimensionally and arranged in a matrix in a circuit diagram.

[0021] Each of the write wirings WL is used when writing data. Each of the write wirings WL electrically connects the control device 3 to one or more domain wall motion elements 100. Each of the common wirings CL is used when writing and reading data. Each of the common wirings CL is connected to, for example, a resistance detection device 4. The common wiring CL may be provided for each of the multiple domain wall motion elements 100, or may be provided across the multiple domain wall motion elements 100. Each of the read wirings RL is used when reading data. Each of the read wirings RL electrically connects the control device 3 to one or more domain wall motion elements 100.

[0022] The first switch SW1, the second switch SW2, and the third switch SW3 are elements that control the flow of current. The first switch SW1, the second switch SW2, and the third switch SW3 are, for example, elements that utilize a phase change of a crystal layer such as a transistor or an Ovonic Threshold Switch (OTS), elements that utilize a change in band structure such as a Metal-Insulator Transition (MIT) switch, elements that utilize a breakdown voltage such as a Zener diode or an avalanche diode, or elements whose conductivity changes with a change in atomic position.

[0023] The first switch SW1 and the second switch SW2 are connected, for example, one to each of the domain wall motion elements 100. The first switch SW1 is connected, for example, between the domain wall motion element 100 and the write wiring WL. The second switch SW2 is connected, for example, between the domain wall motion element 100 and the common wiring CL. The third switch SW3 is connected, for example, across a plurality of domain wall motion elements 100. The third switch SW3 is connected, for example, to the read wiring RL.

[0024] The positional relationship between the first switch SW1, the second switch SW2, and the third switch SW3 is not limited to that shown in Fig. 2. For example, the first switch SW1 may be connected across multiple domain wall motion elements 100 and located upstream of the write wiring WL. Also, for example, the second switch SW2 may be connected across multiple domain wall motion elements 100 and located upstream of the common wiring CL. Also, for example, the third switch SW3 may be connected to each domain wall motion element 100.

[0025] 3 is a cross-sectional view of the vicinity of the domain wall motion element 100 in the integration region 1 according to the first embodiment. Fig. 3 is a cross-section of one domain wall motion element 100 in Fig. 2 taken along the xz plane passing through the center of the width of the first ferromagnetic layer 10 in the y direction.

[0026] The first switch SW1 and the second switch SW2 shown in FIG. 3 are transistors Tr. The transistor Tr has a gate electrode G, a gate insulating film GI, a source S, and a drain D. The source S and the drain D are determined by the direction of current flow and are both semiconductor active regions. FIG. 3 shows only one example, and the positional relationship between the source S and the drain D may be reversed. The substrate Sub is, for example, a semiconductor substrate. The third switch SW3 is electrically connected to the readout wiring RL and is, for example, located at a position shifted in the y direction in FIG. 3.

[0027] The transistor Tr, the write wiring WL, the common wiring CL, the read wiring RL, and the domain wall motion element 100 are connected by via wirings V extending in the z direction or in-plane wirings IP extending in any direction within the xy plane. The via wirings V and the in-plane wirings IP contain a conductive material. An insulating layer 90 is formed between different layers in the z direction, except for the via wirings V.

[0028] The insulating layer 90 is an insulating layer that insulates between wirings in a multilayer wiring structure and between elements. The domain wall motion element 100 and the transistor Tr are electrically isolated by the insulating layer 90, except for the via wiring V. The insulating layer 90 is made of, for example, silicon oxide (SiO x ), silicon nitride (SiNx ), silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO x ) etc.

[0029] Fig. 4 is a cross-sectional view of the domain wall motion device 100 taken along the xz plane passing through the center of the first ferromagnetic layer 10 in the y direction. The arrows in the figure indicate an example of the orientation direction of the magnetization of the ferromagnetic material in the initial state where no external magnetic field is applied to the domain wall motion device 100. Fig. 5 is a plan view of the domain wall motion device 100 as seen from the z direction.

[0030] The domain wall motion element 100 includes, for example, a first ferromagnetic layer 10, a non-magnetic layer 20, a second ferromagnetic layer 30, a first magnetization fixed part 40, a second magnetization fixed part 50, a first electrode E1, a second electrode E2, and a third electrode E3. Each of the multiple domain wall motion elements included in the integration region 1 is the domain wall motion element 100 shown in FIGS. 4 and 5.

[0031] The first ferromagnetic layer 10 extends in the x direction. When viewed from the z direction, the length of the first ferromagnetic layer 10 in the x direction is longer than the length in the y direction. The first ferromagnetic layer 10 has two magnetic domains therein, and a domain wall DW is formed at the boundary between the two magnetic domains. The first ferromagnetic layer 10 is a layer capable of magnetically recording information by changing its magnetic state, for example. The first ferromagnetic layer 10 is also called an analog layer, a magnetic recording layer, or a domain wall displacement layer.

[0032] The first ferromagnetic layer 10 has a first magnetization region A1, a second magnetization region A2, and a third magnetization region A3.

[0033] The first magnetization region A1 has a magnetization M A1 The first magnetization region A1 is a region in which the orientation direction of the magnetization M is fixed in one direction. The magnetization being fixed means that the magnetization does not reverse during normal operation of the domain wall motion device 100 (when no external force exceeding the expected value is applied). The first magnetization region A1 is, for example, a region of the first ferromagnetic layer 10 that overlaps with the first magnetization fixed part 40 when viewed from the z direction. The magnetization M of the first magnetization region A1 A1 is, for example, the magnetization M of the first magnetization fixed layer 41 of the first magnetization fixed unit 40.41 is fixed by

[0034] The second magnetization region A2 has magnetization M A2 The magnetization M of the second magnetization region A2 is fixed in one direction. A2 The orientation direction of the magnetization M of the first magnetization region A1 is A1 The magnetization M of the second magnetization region A2 is different from the orientation direction of the A2 The orientation direction of the magnetization M of the first magnetization region A1 is, for example, A1 The second magnetization region A2 is, for example, a region of the first ferromagnetic layer 10 that overlaps with the second magnetization fixed part 50 when viewed from the z direction. The magnetization M of the second magnetization region A2 A2 is, for example, the magnetization M of the third magnetization fixed layer 51 of the second magnetization fixed unit 50. 51 The magnetization configuration shown in Figure 4 can be achieved, for example, by first applying a very strong upward magnetic field to align all the ferromagnetic layers in the same direction, and then removing the magnetic field to return them to a magnetic-field-free state. This process is called initialization.

[0035] The third magnetization region A3 is a region other than the first magnetization region A1 and the second magnetization region A2 of the first ferromagnetic layer 10. The third magnetization region A3 is, for example, a region sandwiched between the first magnetization region A1 and the second magnetization region A2 in the x direction.

[0036] The third magnetization region A3 is a region where the magnetization direction changes and the domain wall DW can move. The third magnetization region A3 is called a domain wall movable region. The third magnetization region A3 has a first magnetic domain A31 and a second magnetic domain A32. The first magnetic domain A31 and the second magnetic domain A32 have magnetization orientation directions opposite to each other. The boundary between the first magnetic domain A31 and the second magnetic domain A32 is the domain wall DW. The magnetization M of the first magnetic domain A31 A31 is, for example, the magnetization M of the first magnetization region A1. A1 The magnetization M of the second magnetic domain A32 is oriented in the same direction. A32 is, for example, the magnetization M of the adjacent second magnetization region A2. A2 The domain wall DW moves in the third magnetization region A3 in principle, and does not invade the first magnetization region A1 or the second magnetization region A2.

[0037] When the volume ratio between the first magnetic domain A31 and the second magnetic domain A32 in the third magnetization region A3 changes, the domain wall DW moves. The domain wall DW moves by applying a write current in the x direction of the third magnetization region A3. For example, when a write current (e.g., a current pulse) in the +x direction is applied to the third magnetization region A3, electrons flow in the -x direction, which is opposite to the current, and the domain wall DW moves in the -x direction. When a current flows from the first magnetic domain A31 to the second magnetic domain A32, electrons spin-polarized in the second magnetic domain A32 are attracted to the magnetization M of the first magnetic domain A31. A31 The magnetization of the first magnetic domain A31 is reversed. A31 When this is reversed, the domain wall DW moves in the +x direction.

[0038] The first ferromagnetic layer 10 is made of a magnetic material. The first ferromagnetic layer 10 may be a ferromagnetic material, a ferrimagnetic material, or a combination of these with an antiferromagnetic material whose magnetic state can be changed by current. The first ferromagnetic layer 10 preferably contains at least one element selected from the group consisting of Co, Ni, Fe, Pt, Pd, Gd, Tb, Mn, Ge, and Ga.

[0039] Examples of materials used for the first ferromagnetic layer 10 include a laminated film of Co and Ni, a laminated film of Co and Pt, a laminated film of Co and Pd, and Co x Fe 1-x Examples of suitable antiferromagnetic materials include a laminated film of B (0≦x≦1) and the same material as the nonmagnetic layer 20 described later, an MnGa-based material, a GdCo-based material, and a TbCo-based material. Ferrimagnetic materials such as MnGa-based materials, GdCo-based materials, and TbCo-based materials have low saturation magnetization, which reduces the threshold current required to move the domain wall DW. Furthermore, laminated films of Co and Ni, Co and Pt, and Co and Pd have high coercive force, which reduces the domain wall DW movement speed. Examples of suitable antiferromagnetic materials include Mn3X (X is Sn, Ge, Ga, Pt, Ir, etc.), CuMnAs, and Mn2Au. The first ferromagnetic layer 10 can also be made of the same material as the second ferromagnetic layer 30 described later. Two or more types of laminated films or materials can also be used.

[0040] The nonmagnetic layer 20 is sandwiched between the first ferromagnetic layer 10 and the second ferromagnetic layer 30 in the z direction. The nonmagnetic layer 20 is an example of a third nonmagnetic layer. The nonmagnetic layer 20 inhibits magnetic coupling between the first ferromagnetic layer 10 and the second ferromagnetic layer 30. The nonmagnetic layer 20 is stacked on one surface of the second ferromagnetic layer 30.

[0041] The nonmagnetic layer 20 is made of, for example, a nonmagnetic insulator, semiconductor, or metal. Preferably, the nonmagnetic layer 20 is, for example, a nonmagnetic insulator. Examples of nonmagnetic insulators include Al2O3, SiO2, MgO, MgAl2O4, and materials in which a portion of the Al, Si, and Mg in these materials is replaced with Zn, Be, Ga, Ti, or the like. These materials have a wide band gap and excellent insulating properties. Examples of nonmagnetic insulators include oxides containing Mg or Al. When the nonmagnetic layer 20 is made of a nonmagnetic insulator, the nonmagnetic layer 20 is a tunnel barrier layer. Examples of nonmagnetic metals include Cu, Au, Ag, and the like. Examples of nonmagnetic semiconductors include Si, Ge, CuInSe2, CuGaSe2, and Cu(In,Ga)Se2.

[0042] The thickness of the nonmagnetic layer 20 is, for example, not less than 20 Å, and may be not less than 25 Å. The thickness of each layer is the average value of the height in the z direction of the layer measured at five different points in the x direction.

[0043] The second ferromagnetic layer 30 sandwiches the nonmagnetic layer 20 with the first ferromagnetic layer 10. The second ferromagnetic layer 30 is located so that at least a portion thereof overlaps with the third magnetization region A3 in the z direction. The second ferromagnetic layer 30 is, for example, closer to the substrate Sub than the first ferromagnetic layer 10.

[0044] The magnetization M of the second ferromagnetic layer 30 30 The magnetization M of the second ferromagnetic layer 30 is more difficult to reverse than the magnetization of the third magnetization region A3 of the first ferromagnetic layer 10. 30 The second ferromagnetic layer 30 is fixed and does not change its direction when an external force strong enough to reverse the magnetization of the third magnetization region A3 is applied. The second ferromagnetic layer 30 is also called a fixed layer or a reference layer.

[0045] The second ferromagnetic layer 30 includes a ferromagnetic material. The second ferromagnetic layer 30 includes, for example, a material that easily provides a coherent tunneling effect between the second ferromagnetic layer 30 and the first ferromagnetic layer 10. The second ferromagnetic layer 30 includes, for example, 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. The second ferromagnetic layer 30 is, for example, Co-Fe, Co-Fe-B, or Ni-Fe. The second ferromagnetic layer 30 may also include a stacked film of Co and Ni, a stacked film of Co and Pt, or a stacked film of Co and Pd.

[0046] The second ferromagnetic layer 30 may be, for example, a Heusler alloy. Heusler alloys are half-metallic and have high spin polarization. Heusler alloys are intermetallic compounds with a chemical composition of XYZ or X2YZ, where X is a transition metal element or a noble metal element of the Co, Fe, Ni, or Cu group on the periodic table, Y is a transition metal element or an element species of X of the Mn, V, Cr, or Ti group, and Z is a typical element of groups III to V. Examples of Heusler alloys include Co2FeSi, Co2FeGe, Co2FeGa, Co2MnSi, and Co2Mn 1-a Fe a Al b Si 1-b , Co2FeGe 1-c Ga c etc.

[0047] The second ferromagnetic layer 30 may have multiple layers and may have a synthetic antiferromagnetic structure (SAF structure). A synthetic antiferromagnetic structure consists of two magnetic layers sandwiching a nonmagnetic spacer layer. The magnetic layers may include, for example, a ferromagnetic material and may also include an antiferromagnetic material such as IrMn or PtMn. The spacer layer may include, for example, at least one selected from the group consisting of Ru, Ir, and Rh.

[0048] The second ferromagnetic layer 30 and the non-magnetic layer 20 are each longer than the third magnetization region A3 in the x direction, for example. The portion where the second ferromagnetic layer 30 and the third magnetization region A3 face each other with the non-magnetic layer 20 sandwiched therebetween is responsible for the resistance change of the domain wall motion element 100. If the length of the third region of the first ferromagnetic layer 10 in the x direction is long, the resistance change of the domain wall motion element 100 becomes gentler, making it easier to classify the resistance change range of the domain wall motion element 100 into more values. Furthermore, if the proportion of the third magnetization region A3 in the first ferromagnetic layer 10 is larger than the proportions of the first magnetization region A1 and the second magnetization region A2, the resistance change range of the domain wall motion element 100 can be made larger, making detection easier.

[0049] The second ferromagnetic layer 30 is, for example, longer in the x direction than the first ferromagnetic layer 10. When the second ferromagnetic layer 30 overlaps the entire first ferromagnetic layer 10 as viewed in the z direction, the heat dissipation of the first ferromagnetic layer 10 is improved. As a result, the stability of the magnetization of the first magnetization region A1 and the magnetization of the second magnetization region A2 is improved, and the reliability of the data of the domain wall motion element 100 is improved.

[0050] The first magnetization fixed unit 40 is connected to the first ferromagnetic layer 10. The first magnetization fixed unit 40 is connected to the first magnetization region A1. The first magnetization fixed unit 40 fixes the magnetization M of the first magnetization region A1. A1 There is no particular limitation on the shape of the first magnetization fixed unit 40 in a plan view. The shape of the first magnetization fixed unit 40 in a plan view may be rectangular as shown in FIG. 5, or may be circular, for example.

[0051] 6 is a cross-sectional view of the first magnetization fixed unit 40 according to the first embodiment. The first magnetization fixed unit 40 includes a first magnetization fixed layer 41, a first non-magnetic layer 42, and a second magnetization fixed layer 43.

[0052] The first magnetization pinned layer 41 and the second magnetization pinned layer 43 are antiferromagnetically coupled with the first nonmagnetic layer 42 sandwiched therebetween. Here, what is antiferromagnetically coupled is the magnetization of the entire second magnetization pinned layer 43 and the magnetization of the first magnetization pinned layer 41. The magnetic coupling occurs due to RKKY interaction.

[0053] The first magnetization pinned layer 41 is in contact with the first ferromagnetic layer 10. An intermediate layer having a thickness sufficient to maintain the magnetic coupling between the first magnetization pinned layer 41 and the first ferromagnetic layer 10 may be provided between the first magnetization pinned layer 41 and the first ferromagnetic layer 10. The first magnetization pinned layer 41 is a ferromagnetic material. The first magnetization pinned layer 41 is a single layer. For example, the same material as that of the first ferromagnetic layer 10 or the second ferromagnetic layer 30 can be used for the first magnetization pinned layer 41.

[0054] The first non-magnetic layer 42 is located between the first magnetization fixed layer 41 and the second magnetization fixed layer 43 in the z direction. The first non-magnetic layer 42 is in contact with the first magnetization fixed layer 41. The first non-magnetic layer 42 includes, for example, a non-magnetic metal, alloy, or compound. The first non-magnetic layer 42 is, for example, a metal, alloy, or compound containing an element with an atomic number of 39 or greater. The first non-magnetic layer 42 is, for example, Ru, Ir, or Rh.

[0055] The second magnetization fixed layer 43 has a first anti-diffusion structure 46. The second magnetization fixed layer 43 includes, for example, a first layer 45 including a ferromagnetic material, the first anti-diffusion structure 46, and a second layer 47 including a ferromagnetic material. The second layer 47 is an example of a second region.

[0056] The second magnetization fixed layer 43 exhibits ferromagnetism as a whole. The overall magnetization of the second magnetization fixed layer 43 is the sum of the magnetizations of the ferromagnetic materials that make up the second magnetization fixed layer 43. For example, the overall magnetization of the second magnetization fixed layer 43 is the sum of the magnetization of the first layer 45, the magnetization of the ferromagnetic materials that make up the first diffusion prevention structure 46, and the magnetization of the second layer 47.

[0057] The first layer 45 is in contact with the first nonmagnetic layer 42. The first layer 45 includes a ferromagnetic material. For example, the same material as that of the first ferromagnetic layer 10 or the second ferromagnetic layer 30 can be used for the first layer 45. The magnetization M of the first layer 45 45 and the magnetization M of the first magnetization fixed layer 41 41 are antiferromagnetically coupled. The magnetic coupling occurs due to the RKKY interaction.

[0058] The second layer 47 is in contact with the first electrode E1. The second layer 47 includes a ferromagnetic material. For example, the same material as that of the first ferromagnetic layer 10 or the second ferromagnetic layer 30 can be used for the second layer 47. The magnetization M of the second layer 47 47 is the magnetization M of the first layer 45 45 When the magnetization of the second layer 47 and the magnetization of the first layer 45 are aligned in the same direction, the saturation magnetization of the magnetization of the entire second magnetization fixed layer 43 increases, and the magnetization stability of the entire second magnetization fixed layer 43 increases.

[0059] The first diffusion prevention structure 46 is located between the first layer 45 and the second layer 47 in the z direction. The first diffusion prevention structure 46 may be a single layer or multiple layers. Figure 6 illustrates an example in which the first diffusion prevention structure 46 is a multiple layer structure.

[0060] The first diffusion prevention structure 46 includes, for example, a plurality of intermediate ferromagnetic layers 48A, 48B, 48C, 48D, and 48E and a plurality of intermediate non-magnetic layers 49A, 49B, 49C, 49D, 49E, and 49F. Each intermediate ferromagnetic layer is sandwiched between intermediate non-magnetic layers in the z direction.

[0061] There is no particular limitation on the number of intermediate ferromagnetic layers and intermediate non-magnetic layers in the first diffusion prevention structure 46. When adjacent intermediate ferromagnetic layers are antiferromagnetically coupled and the number of intermediate ferromagnetic layers is odd, the main directions of the magnetization orientations of the first layer 45 and the second layer 47 are the same.

[0062] Magnetization M of the intermediate ferromagnetic layer 48A 48A is the magnetization M of the first layer 45 45 The magnetization M of the intermediate ferromagnetic layer 48A is 48A is the magnetization M of the middle ferromagnetic layer 48B 48B The magnetization M of the intermediate ferromagnetic layer 48B is 48B is the magnetization M of the intermediate ferromagnetic layer 48C 48C The magnetization M of the intermediate ferromagnetic layer 48C is 48C is the magnetization M of the intermediate ferromagnetic layer 48D 48D The magnetization M of the intermediate ferromagnetic layer 48D is 48Dis the magnetization M of the intermediate ferromagnetic layer 48E 48E The first diffusion prevention structure 46 may include multiple ferromagnetic layers that are antiferromagnetically coupled. When the ferromagnetic layers that make up the first diffusion prevention structure 46 are antiferromagnetically coupled to each other, the leakage magnetic field from the first diffusion prevention structure 46 is reduced. The magnetic coupling occurs due to the RKKY interaction.

[0063] Each of the intermediate ferromagnetic layers 48A, 48B, 48C, 48D, and 48E can be made of, for example, the same material as the first ferromagnetic layer 10 or the second ferromagnetic layer 30. The thickness of each of the intermediate ferromagnetic layers 48A, 48B, 48C, 48D, and 48E is thinner than the thickness of the first layer 45 and the second layer 47, for example.

[0064] The intermediate non-magnetic layers 49A, 49B, 49C, 49D, 49E, and 49F can each be made of the same material as the first non-magnetic layer 42. Each of the intermediate non-magnetic layers 49A, 49B, 49C, 49D, 49E, and 49F is, for example, a metal, alloy, or compound containing an element with an atomic number of 39 or greater. Heavy elements with an atomic number of 39 or greater prevent element diffusion. Each of the intermediate non-magnetic layers 49A, 49B, 49C, 49D, 49E, and 49F may be a metal film, oxide film, nitride film, or the like containing Ta, Ti, Al, or Si, or a precious metal film.

[0065] The total thickness of the nonmagnetic layers included in the first anti-diffusion structure 46 is preferably 50 Å or more, and more preferably 100 Å or more. In the example shown in Fig. 6, the total thickness of the intermediate nonmagnetic layers 49A, 49B, 49C, 49D, 49E, and 49F corresponds to the total thickness of the nonmagnetic layers included in the first anti-diffusion structure 46. The thickness of each of the intermediate nonmagnetic layers 49A, 49B, 49C, 49D, 49E, and 49F is, for example, a thickness that allows adjacent intermediate ferromagnetic layers to be antiferromagnetically coupled by RKKY interaction.

[0066] The second magnetization fixed unit 50 is connected to the first ferromagnetic layer 10 at a position separated from the first magnetization fixed unit 40 in the x direction. The second magnetization fixed unit 50 is connected to the second magnetization region A2. The second magnetization fixed unitA2 The shape of the second magnetization fixed unit 50 in plan view may be, for example, rectangular as shown in FIG. 5, or circular.

[0067] 7 is a cross-sectional view of the second magnetization fixed unit 50 according to the first embodiment. The second magnetization fixed unit 50 includes a third magnetization fixed layer 51, a second non-magnetic layer 52, and a fourth magnetization fixed layer 53.

[0068] The third magnetization pinned layer 51 and the fourth magnetization pinned layer 53 are antiferromagnetically coupled with the second nonmagnetic layer 52 sandwiched therebetween. Here, what is antiferromagnetically coupled is the magnetization of the entire fourth magnetization pinned layer 53 and the magnetization of the third magnetization pinned layer 51. The magnetic coupling occurs due to RKKY interaction.

[0069] The third magnetization pinned layer 51 is in contact with the first ferromagnetic layer 10. An intermediate layer having a thickness sufficient to maintain the magnetic coupling between the third magnetization pinned layer 51 and the first ferromagnetic layer 10 may be provided between the third magnetization pinned layer 51 and the first ferromagnetic layer 10. The third magnetization pinned layer 51 is a ferromagnetic material. The third magnetization pinned layer 51 is a single layer. For example, the same material as that of the first ferromagnetic layer 10 or the second ferromagnetic layer 30 can be used for the third magnetization pinned layer 51. The thickness of the third magnetization pinned layer 51 is the same as that of the first magnetization pinned layer 41.

[0070] The second non-magnetic layer 52 is located between the third magnetization fixed layer 51 and the fourth magnetization fixed layer 53 in the z direction. The second non-magnetic layer 52 is in contact with the third magnetization fixed layer 51. The second non-magnetic layer 52 can be made of the same material as the first non-magnetic layer 42. The thickness of the second non-magnetic layer 52 is the same as the thickness of the first non-magnetic layer 42.

[0071] The fourth magnetization fixed layer 53 has a second anti-diffusion structure 56. The fourth magnetization fixed layer 53 includes, for example, a third layer 55 including a ferromagnetic material, the second anti-diffusion structure 56, and a fourth layer 57 including a ferromagnetic material. The fourth layer 57 is an example of a first region.

[0072] The fourth magnetization fixed layer 53 exhibits ferromagnetism as a whole. The overall magnetization of the fourth magnetization fixed layer 53 is the sum of the magnetizations of the ferromagnetic materials that make up the fourth magnetization fixed layer 53. For example, the overall magnetization of the fourth magnetization fixed layer 53 is the sum of the magnetization of the third layer 55, the magnetization of the ferromagnetic materials that make up the second diffusion prevention structure 56, and the magnetization of the fourth layer 57.

[0073] The third layer 55 is in contact with the second nonmagnetic layer 52. The third layer 55 includes a ferromagnetic material. For example, the same material as that of the first ferromagnetic layer 10 or the second ferromagnetic layer 30 can be used for the third layer 55. The magnetization M of the third layer 55 55 and the magnetization M of the third magnetization fixed layer 51 51 are antiferromagnetically coupled. The magnetic coupling occurs due to the RKKY interaction.

[0074] The fourth layer 57 is in contact with the second electrode E2. The fourth layer 57 is located farther from the second nonmagnetic layer 52 than the second anti-diffusion structure 56. The fourth layer 57 includes a ferromagnetic element and a nonmagnetic element. The fourth layer 57 is a layer formed by ion-implanting a nonmagnetic element into a ferromagnetic layer. By ion-implanting the nonmagnetic element into the ferromagnetic layer, the saturation magnetization of the fourth layer 57 is smaller than the saturation magnetization of the second layer 47. The fourth layer 57 may have nonmagnetic properties as a whole.

[0075] The ferromagnetic element constituting the fourth layer 57 is the same as the ferromagnetic element contained in the second layer 47 .

[0076] The non-magnetic element constituting the fourth layer 57 is, for example, a rare gas. Because the rare gas has a larger atomic radius than other elements, it can disrupt the magnetization arrangement of the ferromagnetic material and reduce the saturation magnetization of the fourth layer 57. The rare gas is, for example, He, Ar, Kr, or Xe, and may be one type or two or more types.

[0077] The non-magnetic element constituting the fourth layer 57 may be, for example, at least one element selected from the group consisting of B, N, O, F, and Ga. The non-magnetic element constituting the fourth layer 57 is preferably, for example, at least one element selected from the group consisting of N, O, F, and Ga. Elements with a larger atomic weight than B, such as N, O, F, and Ga, have a larger kinetic energy during ion implantation and can be implanted deeper. As a result, using these elements facilitates processing by element implantation.

[0078] The non-magnetic element constituting the fourth layer 57 is, for example, an element not contained in the second layer 47.

[0079] The second diffusion prevention structure 56 is located between the third layer 55 and the fourth layer 57 in the z direction. The second diffusion prevention structure 56 may be a single layer or multiple layers. FIG. 7 illustrates a case where the second diffusion prevention structure 56 is multiple layers. The second diffusion prevention structure 56 prevents the non-magnetic element contained in the fourth layer 57 from diffusing toward the third layer 55. When the second diffusion prevention structure 56 is made up of multiple layers including a ferromagnetic layer and a non-magnetic layer, the non-magnetic element contained in the fourth layer 57 can be prevented from diffusing toward the third layer 55.

[0080] The second diffusion prevention structure 56 includes, for example, a plurality of intermediate ferromagnetic layers 58A, 58B, 58C, 58D, and 58E and a plurality of intermediate non-magnetic layers 59A, 59B, 59C, 59D, 59E, and 59F. Each intermediate ferromagnetic layer is sandwiched between intermediate non-magnetic layers in the z direction.

[0081] The number of intermediate ferromagnetic layers and intermediate non-magnetic layers in the second diffusion prevention structure 56 is the same as the number of intermediate ferromagnetic layers and intermediate non-magnetic layers in the first diffusion prevention structure 46 .

[0082] The second diffusion prevention structure 56 may include multiple ferromagnetic layers therein that are antiferromagnetically coupled.

[0083] The intermediate ferromagnetic layers 58A, 58B, 58C, 58D, and 58E have the same configuration as the intermediate ferromagnetic layers 48A, 48B, 48C, 48D, and 48E, respectively.

[0084] The configuration of each of the intermediate non-magnetic layers 59A, 59B, 59C, 59D, 59E, and 59F is similar to that of the intermediate non-magnetic layers 49A, 49B, 49C, 49D, 49E, and 49F, respectively. Each of the intermediate non-magnetic layers 59A, 59B, 59C, 59D, 59E, and 59F is, for example, a metal, alloy, or compound containing an element with an atomic number of 39 or greater.

[0085] The total thickness of the nonmagnetic layers included in the second diffusion prevention structure 56 is preferably 50 Å or more, and more preferably 100 Å or more. In the example shown in FIG. 7 , the total thickness of the middle nonmagnetic layers 59A, 59B, 59C, 59D, 59E, and 59F corresponds to the total thickness of the nonmagnetic layers included in the second diffusion prevention structure 56. If the total thickness of the nonmagnetic layers included in the second diffusion prevention structure 56 is sufficiently thick, the nonmagnetic element included in the fourth layer 57 can be more effectively prevented from diffusing toward the third layer 55. It is desirable that the concentration of the nonmagnetic element included in the second diffusion prevention structure 56 be lower on the side closer to the third layer 55 than on the side closer to the fourth layer 57.

[0086] Here, the positional relationship between the first magnetization fixed unit 40 and the second magnetization fixed unit 50 is not limited to the example shown in Fig. 4. The positional relationship between the first magnetization fixed unit 40 and the second magnetization fixed unit 50 may be reversed, and the first magnetization fixed unit 40 may be located in the +x direction of the second magnetization fixed unit 50.

[0087] The first electrode E1 is connected to the first magnetization fixed unit 40. The first electrode E1 may be in direct contact with the first magnetization fixed unit 40, or may be indirectly connected via a layer. The first electrode E1 is, for example, a write electrode used when applying a write current to the domain wall motion element 100. The write current flows between the first electrode E1 and the second electrode E2. The first electrode E1 includes a conductive material.

[0088] The second electrode E2 is connected to the second magnetization fixed unit 50. The second electrode E2 may be in direct contact with the second magnetization fixed unit 50, or may be indirectly connected via a layer. The second electrode E2 is a common electrode used when applying a write current to the domain wall motion element 100 and when applying a read current to the domain wall motion element 100. The second electrode E2 includes a conductive material.

[0089] The third electrode E3 is connected to the second ferromagnetic layer 30. The third electrode E3 may be in direct contact with the second ferromagnetic layer 30, or may be indirectly connected via a layer. The third electrode E3 is a read electrode used when applying a read current to the domain wall motion element 100. The third electrode E3 includes a conductive material.

[0090] The domain wall motion element 100 may have layers other than those described above. For example, a magnetic layer may be provided on the surface of the second ferromagnetic layer 30 opposite the nonmagnetic layer 20, with a spacer layer interposed therebetween. The second ferromagnetic layer 30, the spacer layer, and the magnetic layer form a synthetic antiferromagnetic structure (SAF structure). An underlayer may also be provided on the surface of the magnetic layer opposite the spacer layer.

[0091] The magnetization direction of each layer of the domain wall motion device 100 can be confirmed by, for example, measuring a magnetization curve. The magnetization curve can be measured using, for example, MOKE (Magneto Optical Kerr Effect). Measurement using MOKE is a measurement method in which linearly polarized light is incident on the object to be measured and the magneto-optical effect (magnetic Kerr effect) is used to cause the rotation of the polarization direction, etc.

[0092] The method for manufacturing the domain wall motion element 100 includes a lamination step of each layer, a processing step of processing a part of each layer into a predetermined shape, and an element injection step of injecting a non-magnetic element into a part of the magnetization fixed portion.

[0093] In the stacking process, a layer to become the second ferromagnetic layer 30, a layer to become the nonmagnetic layer 20, a layer to become the first ferromagnetic layer 10, a layer to become the first magnetization pinned layer 41 and the third magnetization pinned layer 51, a layer to become the first nonmagnetic layer 42 and the second nonmagnetic layer 52, a layer to become the first layer 45 and the third layer 55, a layer to become the first diffusion prevention structure 46 and the second diffusion prevention structure 56, and a layer to become the second layer 47 and the fourth layer 57 are stacked in this order on the third electrode E3. The layers can be stacked by sputtering, chemical vapor deposition (CVD), electron beam evaporation (EB evaporation), atomic laser deposition, or the like.

[0094] In the processing step, a part of the laminate formed in the laminating step is processed. The processing of the laminate can be performed using photolithography and etching (for example, Ar etching or reactive ion etching), etc.

[0095] The processing step includes an outer shape forming step and a magnetization fixed portion forming step.

[0096] In the outer diameter forming step, the outer shape of the laminate is determined.

[0097] In the magnetization fixed portion forming step, layers of the laminate that will become the magnetization fixed portions are processed. The layers that will become the first magnetization fixed layer 41 and the third magnetization fixed layer 51, the first non-magnetic layer 42 and the second non-magnetic layer 52, the first layer 45 and the third layer 55, the first diffusion prevention structure 46 and the second diffusion prevention structure 56, and the second layer 47 and the fourth layer 57. By processing these layers so as to separate them in the x direction, two magnetization fixed portions are formed on the first ferromagnetic layer 10.

[0098] In the element injection process, a non-magnetic element is injected into one of the ferromagnetic layers of the two magnetization fixed units. For example, the non-magnetic element is injected into the ferromagnetic layer located at a position corresponding to the fourth layer 57. The non-magnetic element can be injected by a known method. For example, ion injection, plasma doping, laser doping, etc. are some of the methods for doping a ferromagnetic material with a non-magnetic element. The ferromagnetic layer located at a position corresponding to the fourth layer 57 is doped with a non-magnetic element, thereby reducing the saturation magnetization. The reduction in the saturation magnetization of the fourth layer 57 creates a difference in coercivity between the first magnetization fixed unit 40 and the second magnetization fixed unit 50. By utilizing this difference in coercivity, the magnetization M of the first magnetization fixed layer 41 can be reduced. 41 and the magnetization M of the third magnetization fixed layer 51 51 and can be oriented in opposite directions.

[0099] When a coercive force difference is created by etching a part of the magnetization fixed portion, the etching progress may vary. In contrast, the domain wall motion device 100 according to this embodiment can create a coercive force difference without etching.

[0100] Next, the operation of writing a signal to the magnetic array MA and the operation of reading a signal from the magnetic array MA will be described.

[0101] First, the operation of writing a signal to the magnetic array MA will be described. The write operation is performed by, for example, having a processor execute an operation program stored in the control unit 6.

[0102] First, the control device 3 selects the domain wall motion element 100 to which a pulse is to be applied in accordance with the operation program. When the magnetic array MA is used as a magnetic memory, the domain wall motion element 100 to which the pulse is applied is an element that stores data. When the magnetic array MA is used as a neural network, the domain wall motion element 100 to which the pulse is applied is an element that changes the weight in accordance with learning.

[0103] The control unit 6 controls which of the multiple domain wall motion elements 100 to apply a pulse to. The control unit 6 turns on the first switch SW1 and the second switch SW2 connected to the domain wall motion element 100 to which the pulse is to be applied, and turns off the third switch SW3. The control unit 6 also turns off at least one of the first switch SW1 and the second switch SW2 connected to the domain wall motion element 100 to which the pulse is not to be applied.

[0104] Then, the control device 3 outputs a write pulse to the domain wall motion element 100 in accordance with the operation program. The write pulse is applied between the first magnetization pinned unit 40 and the second magnetization pinned unit 50 along the first ferromagnetic layer 10 of the domain wall motion element 100. The write pulse may be a square wave, a spike wave, or a wave with another waveform. By changing the number of write pulses, the magnitude, etc., the position of the domain wall DW changes, and a signal is written to a specific domain wall motion element 100.

[0105] Next, the operation of reading a signal from the magnetic array MA will be described. The reading operation is performed by, for example, having a processor execute an operation program stored in the control unit 6.

[0106] First, the control device 3 selects the domain wall motion element 100 to which a read pulse is applied in accordance with the operation program. When the magnetic array MA is used as a magnetic memory, the domain wall motion element 100 to which the read pulse is applied is the element that reads data. When the magnetic array MA is used as a neural network, the application of a read pulse to a specific domain wall motion element 100 corresponds to a multiplication operation of the input and the weight. In other words, when the magnetic array MA is used as a neural network, the read operation is an identification operation of the neural network.

[0107] The control unit 6 controls which of the multiple domain wall motion elements 100 to apply a pulse to. The control unit 6 turns on the third switch SW3 and the second switch SW2 connected to the domain wall motion element 100 to which the pulse is to be applied, and turns off the first switch SW1. The control unit 6 also turns off at least one of the third switch SW3 and the second switch SW2 connected to the domain wall motion element 100 to which the pulse is not to be applied.

[0108] Next, the control device 3 applies a read pulse to a predetermined domain wall motion element 100 in accordance with the operation program. The read pulse is applied, for example, between the third wiring W3 and the first magnetization fixed unit 40. The voltage of the read pulse is a voltage that provides a current density less than the critical current density required to move the domain wall DW of the first ferromagnetic layer 10. In other words, the read pulse does not move the domain wall DW.

[0109] The resistance detection device 4 detects the resistance value of the domain wall motion element 100 to which the read pulse has been applied. The output unit 5 outputs the calculation result to the outside, for example. By this procedure, a signal can be read out from a specific domain wall motion element 100.

[0110] In the domain wall motion element 100 according to this embodiment, a non-magnetic element is doped into a portion of the ferromagnetic layer, thereby creating a coercive force difference between the first magnetization pinned part 40 and the second magnetization pinned part 50. When creating a coercive force difference using etching, it is necessary to control the progress of the etching, but in the manufacturing method for the domain wall motion element 100 according to this embodiment, such control is not necessary.

[0111] Furthermore, since the domain wall motion element 100 according to this embodiment has the second diffusion prevention structure 56, it is possible to limit the range into which the non-magnetic element is doped. As a result, the domain wall motion element 100 according to this embodiment can control the stability of the magnetization of the first ferromagnetic layer 10 to a desired value. The domain wall motion element 100 with high magnetization stability has excellent operational stability and high reliability of stored data.

[0112] Furthermore, when multiple domain wall motion elements 100 are arranged in the integration region 1, the diffusion prevention structure can be used to define the range in which the non-magnetic elements diffuse, thereby reducing the variation in the magnetization state of each element. A magnetic array in which the multiple domain wall motion elements 100 arranged in the integration region 1 have small variations is highly versatile and has high reliability in the output signals.

[0113] The domain wall motion device 100 according to the first embodiment can be used in, for example, a magnetic memory or a neuromorphic device.

[0114] In the case of a magnetic memory, each of the domain wall motion elements 100 functions as an element for storing data. The resistance of the domain wall motion element 100 changes depending on the position of the domain wall DW of the domain wall motion element 100, and this resistance value is used to store data.

[0115] In the case of a neuromorphic device, each of the domain wall motion elements 100 functions as a product calculation element. The resistance of the domain wall motion element 100 changes depending on the position of the domain wall DW of the domain wall motion element, and this resistance value represents the weight.

[0116] A neuromorphic device is a device that artificially mimics the relationship between neurons and synapses in the human brain. Neuromorphic devices are capable of performing neural network calculations.

[0117] Figure 8 is a schematic diagram of a neural network NN. The neural network NN has an input layer L in and the middle class L m and the output layer L out In FIG. 8, the intermediate layer L m presents a three-layer example, but the middle layer L m The number of input layers L in and the middle class L m and the output layer L out Each of the input layers L has multiple nodes N, each of which corresponds to a neuron in the brain. in and the middle class L m and the output layer L outThe nodes N and the number of transmission means shown in FIG. 8 are examples. In FIG. 8, the input layer L in We present an example where the input layer L consists of two nodes. in , middle layer L m , output layer L out The number of nodes that make up the network is not important.

[0118] A neural network (NN) improves the rate of correct answers to questions by learning through its transmission means (synapses). Learning is the process of finding knowledge that may be useful in the future from information. A neural network (NN) learns by operating while changing the weights of its transmission means. The transmission means performs a multiplication operation to apply a weight to the input signal, and a sum operation to add the result of the multiplication operation. In other words, the transmission means performs a product-sum operation. The domain wall motion device 100 according to this embodiment is responsible for this multiplication operation.

[0119] 9 is a block diagram showing a system 300 including the neuromorphic device 200 according to the first embodiment. The system 300 includes a plurality of sensors 201, the neuromorphic device 200, and a communication unit 202.

[0120] Any sensor can be used for each of the multiple sensors 201 depending on the application. For example, a temperature sensor, a humidity sensor, a speed sensor, a pressure sensor, an acceleration sensor, etc. can be used as the multiple sensors 201. The signals from these sensors are input to, for example, an input layer L in corresponds to the signal input to

[0121] The neuromorphic device 200 has, for example, multiple accumulation regions 1. Each accumulation region 1 performs a product-sum operation. Each accumulation region 1 performs operations from each layer of the neural network NN to the next layer. Each accumulation region 1 may have a separate control device 3, or may share the control device 3.

[0122] The conductance (or resistance) of the domain wall motion element 100 changes depending on the position of the domain wall DW. The conductance (or resistance) of the domain wall motion element 100 corresponds to the weight of the transmission means in the neural network NN. The conductance (or resistance) of the domain wall motion element 100 changes linearly with respect to the input. For example, if information (e.g., temperature) from a specific sensor 201 among the multiple sensors 201 is important, the conductance (weight) of the domain wall motion element 100 responsible for transmitting the signal from that sensor 201 is increased when the neuromorphic device 200 learns.

[0123] The domain wall motion element 100 functions as a product calculation element because it outputs the product of the input voltage and the conductance (or resistance) of the domain wall motion element 100 itself as a signal. The magnetic array MA functions as a product-sum calculator because it combines the outputs from multiple domain wall motion elements 100. The product-sum calculation by the multiple domain wall motion elements 100 is controlled by the control device 3.

[0124] The neuromorphic device 200 performs learning and inference. The conductance (corresponding to the weight of the transmission means) of the domain wall motion element 100 is adjusted during learning. Inference is performed using the set conductance (corresponding to the weight of the transmission means) of the domain wall motion element 100.

[0125] The neuromorphic device 200 used in the system 300 may be capable of both learning and inference, or may be capable of only inference. When only inference is performed, learning tailored to the task is performed in advance, and weights tailored to the task are installed in the domain wall motion elements 100 of the neuromorphic device 200. For example, the conductance of each domain wall motion element 100 is adjusted so that it corresponds to the weight of the transmission means determined in the advance learning. If the neuromorphic device 200 is capable of only inference, the computational load on the edge device can be reduced.

[0126] The communication unit 202 outputs the calculation results of the neuromorphic device 200 to the outside. For example, an inference result for a predetermined task obtained by the neuromorphic device 200 is input to the communication unit 202, and the communication unit 202 outputs the information to the outside. The communication unit 202 may be wired or wireless.

[0127] The domain wall motion device 100 according to this embodiment has small variations between devices and excellent operational stability, and therefore the reliability of the system 300 is high.

[0128] Although the preferred embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to this embodiment.

[0129] For example, although the examples in which the ferromagnetic layers constituting the first diffusion prevention structure 46 and the second diffusion prevention structure 56 are antiferromagnetically coupled have been shown, these ferromagnetic layers may also be ferromagnetically coupled.

[0130] Although the first diffusion prevention structure 46 and the second diffusion prevention structure 56 are each made up of multiple layers in the above example, the first diffusion prevention structure 46 and the second diffusion prevention structure 56 may be a single layer. That is, the first diffusion prevention structure 46 may be a single-layer first diffusion prevention layer, and the second diffusion prevention structure 56 may be a single-layer second diffusion prevention layer.

[0131] The number of ferromagnetic layers and non-magnetic layers constituting the first magnetization pinned unit and the second magnetization pinned unit is not limited to these examples and may be any number. Furthermore, the domain wall motion element may not have the non-magnetic layer 20 and the second ferromagnetic layer 30. In this case, the domain wall motion element functions as, for example, a magneto-optical element. [Explanation of symbols]

[0132] 1. Accumulation Area 2. Surrounding Areas 3. Control device 4 Resistance detection device 5 Output section 6 Control Unit 7 Power supply 10 First ferromagnetic layer 20 Nonmagnetic layer 30 Second ferromagnetic layer 40 First magnetization fixed part 41 First magnetization fixed layer 42 First nonmagnetic layer 43 Second magnetization fixed layer 45 1st layer 46 First diffusion prevention structure 47 Second layer (second area) 48A, 48B, 48C, 48D, 48E, 58A, 58B, 58C, 58D, 58E Intermediate ferromagnetic layer 49A, 49B, 49C, 49D, 49E, 49F, 59A, 59B, 59C, 59D, 59E, 59F Intermediate nonmagnetic layer 50 Second magnetization fixed part 51 Third magnetization fixed layer 52 Second nonmagnetic layer 53 4th magnetization fixed layer 55 3rd layer 56 Second diffusion prevention structure 57 4th layer (1st area) 90 Insulating layer 100 Domain wall motion element 200 Neuromorphic Devices 201 Sensors 202 Communications Department 300 System E1 1st electrode E2 2nd electrode E3 3rd electrode MA magnetic array

Claims

1. a first ferromagnetic layer having a domain wall therein; a first magnetization fixed unit connected to the first ferromagnetic layer; a second magnetization fixed unit connected to the first ferromagnetic layer at a position spaced apart from the first magnetization fixed unit, the first magnetization fixed unit includes a first magnetization fixed layer, a first non-magnetic layer, and a second magnetization fixed layer, the first magnetization fixed layer and the second magnetization fixed layer are antiferromagnetically coupled with the first nonmagnetic layer interposed therebetween, the first magnetization fixed layer is in contact with the first ferromagnetic layer, the first nonmagnetic layer is located between the first magnetization fixed layer and the second magnetization fixed layer in the stacking direction; the second magnetization fixed layer has a first diffusion prevention structure, the second magnetization fixed unit includes a third magnetization fixed layer, a second non-magnetic layer, and a fourth magnetization fixed layer, the third magnetization fixed layer and the fourth magnetization fixed layer are antiferromagnetically coupled with the second nonmagnetic layer interposed therebetween, the third magnetization fixed layer is in contact with the first ferromagnetic layer, the second nonmagnetic layer is located between the third magnetization fixed layer and the fourth magnetization fixed layer in the stacking direction; the fourth magnetization fixed layer has a second diffusion prevention structure and a first region, the first region is located farther from the second nonmagnetic layer than the second diffusion prevention structure, The first region includes a ferromagnetic element and a non-magnetic element.

2. The domain wall motion element according to claim 1 , wherein the first diffusion prevention structure includes a plurality of ferromagnetic layers therein that are antiferromagnetically coupled.

3. The domain wall motion element according to claim 1 , wherein the first diffusion prevention structure includes a plurality of ferromagnetic layers that are ferromagnetically coupled therein.

4. The domain wall motion element according to claim 1 , wherein the second diffusion prevention structure includes a plurality of ferromagnetic layers therein that are antiferromagnetically coupled.

5. The domain wall motion element according to claim 1 , wherein the second diffusion prevention structure includes a plurality of ferromagnetic layers that are ferromagnetically coupled therein.

6. the first diffusion prevention structure has an intermediate nonmagnetic layer therein; 2. The domain wall motion element according to claim 1, wherein the intermediate non-magnetic layer contains an element having an atomic number of 39 or more.

7. the second diffusion prevention structure has an intermediate nonmagnetic layer therein; 2. The domain wall motion element according to claim 1, wherein the intermediate non-magnetic layer contains an element having an atomic number of 39 or more.

8. The domain wall motion element according to claim 1 , wherein the non-magnetic element contained in the first region is a rare gas.

9. 2. The domain wall motion element according to claim 1, wherein the non-magnetic element contained in the first region is at least one element selected from the group consisting of B, N, O, F, and Ga.

10. the second magnetization fixed layer further includes a second region; The domain wall motion element according to claim 1 , wherein the saturation magnetization of the first region is smaller than the saturation magnetization of the second region.

11. the first diffusion prevention structure and the second diffusion prevention structure each have one or more intermediate nonmagnetic layers therein; 2. The domain wall motion element according to claim 1, wherein the number of intermediate non-magnetic layers included in said first diffusion prevention structure is the same as the number of intermediate non-magnetic layers included in said second diffusion prevention structure.

12. further comprising a third non-magnetic layer and a second ferromagnetic layer; 2. The domain wall motion element according to claim 1, wherein the first ferromagnetic layer and the second ferromagnetic layer sandwich the third non-magnetic layer in the stacking direction.

13. A plurality of domain wall motion elements are provided, A magnetic array, wherein each of the plurality of domain wall motion elements is the domain wall motion element according to claim 1 .

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