Domain wall-moving element, magnetic array, neuromorphic device, and method for manufacturing domain wall-moving element

Abstract

This domain wall-moving element comprises: a first ferromagnetic layer that has a domain wall therein; a second ferromagnetic layer; a nonmagnetic layer that is sandwiched between the first ferromagnetic layer and the second ferromagnetic layer; a first fixed magnetization section that is connected to the first ferromagnetic layer; a second fixed magnetization section that is connected to the first ferromagnetic layer at a location that is distanced from the first fixed magnetization section in a first direction; a first electrode that is connected to the first fixed magnetization section; and a second electrode that is connected to the second fixed magnetization section. The second ferromagnetic layer is closer to a substrate than the first ferromagnetic layer. In the first direction, which is from the first fixed magnetization section toward the second fixed magnetization section, the center of the first electrode is located further removed from the center of the first ferromagnetic layer than the center of the first fixed magnetization section. The first fixed magnetization section has a first surface that is in contact with the first ferromagnetic layer, and a second surface that is opposite from the first surface. At least a section of the second surface is not in contact with the first electrode.

Description

Domain wall motion element, magnetic array, neuromorphic device, and method for manufacturing domain wall motion element

[0001] The present disclosure relates to a domain wall motion element, a magnetic array, a neuromorphic device, and a method for manufacturing a domain wall motion element.

[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, a domain wall motion type magnetoresistive effect element (hereinafter referred to as a domain wall motion element) described in Patent Document 1 is an example of a magnetoresistive effect element. In a domain wall motion element, the resistance value in the stacking direction changes depending on the position of the domain wall, and data can be recorded in a multi-value or analog format. A domain wall motion element has high linearity and symmetry in the resistance change, excellent rewrite durability, and is capable of high-speed operation.

[0003] Patent Document 1 describes that magnetization pinned portions for limiting the range of movement of the domain wall are provided at both ends of the first magnetization free layer (domain wall displacement layer). The two magnetization pinned portions have different magnetization orientation directions.

[0004] International Publication No. 2011 / 052475

[0005] A domain wall motion element writes signals by applying a write current. The write current is applied to the domain wall motion element via an electrode connected to the magnetization fixed portion. In order to increase the contact area between the magnetization fixed portion and the electrode, the electrode is often formed at a position overlapping the magnetization fixed portion. However, if the center position of the magnetization fixed portion and the center position of the electrode overlap, the reliability of the domain wall motion element may be reduced.

[0006] The present disclosure has been made in view of the above problems, and aims to provide a highly reliable domain wall motion element, magnetic array, and neuromorphic device.

[0007] A domain wall motion element according to a first aspect includes a first ferromagnetic layer having a domain wall therein, a second ferromagnetic layer, a non-magnetic layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, 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 in a first direction, a first electrode connected to the first magnetization fixed unit, and a second electrode connected to the second magnetization fixed unit. The second ferromagnetic layer is closer to a substrate than the first ferromagnetic layer. In a first direction from the first magnetization fixed unit to the second magnetization fixed unit, the center of the first electrode is located farther from the center of the first ferromagnetic layer than the center of the first magnetization fixed unit. The first magnetization fixed unit has a first surface in contact with the first ferromagnetic layer and a second surface opposite to the first surface. At least a portion of the second surface is not in contact with the first electrode.

[0008] 1 is a block diagram of a magnetic array according to the first embodiment. FIG. 2 is a circuit diagram of an integrated region of the magnetic array according to the first embodiment. FIG. 3 is a cross-sectional view of the vicinity of a domain wall motion element of the magnetic array according to the first embodiment. FIG. 4 is a cross-sectional view of the domain wall motion element according to the first embodiment. FIG. 5 is a plan view of the domain wall motion element according to the first embodiment. FIG. 6 is an enlarged view of the vicinity of the first magnetization fixed layer of the domain wall motion element according to the first embodiment. FIG. 7 is an enlarged view of the vicinity of the second magnetization fixed layer of the domain wall motion element according to the first embodiment. FIG. 8 is a diagram for explaining a manufacturing method of the domain wall motion element according to the first embodiment. FIG. 9 is a diagram for explaining a manufacturing method of the domain wall motion element according to the first embodiment. FIG. 10 is a diagram for explaining a manufacturing method of the domain wall motion element according to the first embodiment. FIG. 11 is a conceptual diagram of a neural network. FIG. 12 is a block diagram showing a system including a neuromorphic device according to the first embodiment. FIG. 13 is a cross-sectional view of the domain wall motion element according to the second embodiment. FIG. 14 is an enlarged view of the vicinity of the first magnetization fixed layer of the domain wall motion element according to the second embodiment. FIG. 15 is an enlarged view of the vicinity of the second magnetization fixed layer of the domain wall motion element according to the second embodiment. FIG. 16 is a cross-sectional view of the domain wall motion element according to the third embodiment. FIG. 17 is an enlarged view of the vicinity of the first magnetization fixed layer of the domain wall motion element according to the third embodiment. FIG. 10 is an enlarged view of the vicinity of the second magnetization fixed layer of the domain wall motion element according to the third embodiment. FIG. 11 is a cross-sectional view of the domain wall motion element according to the fourth embodiment. FIG. 12 is an enlarged view of the vicinity of the first magnetization fixed layer of the domain wall motion element according to the fourth embodiment. FIG. 13 is an enlarged view of the vicinity of the second magnetization fixed layer of the domain wall motion element according to the fourth embodiment. FIG. 14 is a cross-sectional view of the domain wall motion element according to the fifth embodiment. FIG. 15 is an enlarged view of the vicinity of the first magnetization fixed layer of the domain wall motion element according to the fifth embodiment. FIG. 16 is an enlarged view of the vicinity of the second magnetization fixed layer of the domain wall motion element according to the fifth embodiment. FIG. 17 is a cross-sectional view of the domain wall motion element according to the sixth embodiment. FIG. 18 is a cross-sectional view of the domain wall motion element according to the seventh embodiment. FIG. 19 is a cross-sectional view of the domain wall motion element according to the eighth embodiment.

[0009] 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.

[0010] First, the directions will be defined. The x-direction and y-direction 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 x-direction is an example of a first direction. In the following figures, the −x-direction is the first direction. The y-direction is a direction perpendicular to the x-direction. The y-direction is an example of a second direction. The z-direction is a 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-direction, y-direction, and z-direction. The same applies to extending in other directions.

[0011] 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.

[0012] The accumulation region 1 is a region where a plurality of 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.

[0013] 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 unit 5.

[0014] 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.

[0015] 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 (voltage, pulse length) of the pulse 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 indicator of the timing to apply 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.

[0016] 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 has, for example, a comparator that compares the magnitude of the detected resistance value. The comparator may, for example, compare the detected resistance values ​​with each other, or may compare the detected resistance value with a preset reference resistance value.

[0017] 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.

[0018] 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 wirings WL, a plurality of common wirings CL, a plurality of read wirings 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.

[0019] 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 elements that are actually arranged in a matrix, but may be elements that are arranged in a matrix in a circuit diagram.

[0020] 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, the 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.

[0021] 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 may be, for example, an element that uses a phase change of a crystal layer such as a transistor or an Ovonic Threshold Switch (OTS), an element that uses a change in band structure such as a Metal-Insulator Transition (MIT) switch, an element that uses a breakdown voltage such as a Zener diode or an avalanche diode, or an element that changes conductivity according to a change in atomic position.

[0022] 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.

[0023] 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.

[0024] 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 an xz plane passing through the center of the width of the first ferromagnetic layer 10 in the y direction.

[0025] 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, and a source S and a drain D formed on a substrate Sub. 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.

[0026] 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 Vw extending in the z direction or in-plane wirings IPw extending in any direction within the xy plane. The via wirings Vw and the in-plane wirings IPw contain a conductive material. An insulating layer 90 is formed between different layers in the z direction, except for the via wirings Vw.

[0027] 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 Vw. The insulating layer 90 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 ) etc.

[0028] 4 is a cross-sectional view of the domain wall motion element 100 taken along an 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. FIG. 5 is a plan view of the domain wall motion element 100 as seen from the z direction.

[0029] 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 pinned layer 40, a second magnetization pinned layer 50, a first electrode 60, a second electrode 70, and a third electrode 80. At least one of the multiple domain wall motion elements included in the integration region 1 is the domain wall motion element 100 shown in FIGS.

[0030] 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, for example, a layer capable of magnetically recording information by changing its magnetic state. The first ferromagnetic layer 10 is also called an analog layer, a magnetic recording layer, or a domain wall displacement layer.

[0031] The first ferromagnetic layer 10 has a first magnetization region A1, a second magnetization region A2, and a third magnetization region A3.

[0032] 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 element 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 layer 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 40 ４０ is fixed by

[0033] 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 layer 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 second magnetization fixed layer 50 ５０ is fixed by

[0034] 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.

[0035] The third magnetization region A3 is a region where the magnetization direction can change 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 Ａ１The magnetization M of the second magnetic domain A32 is oriented in the same direction as Ａ３２ is, for example, the magnetization M of the adjacent second magnetization region A2. Ａ２ In principle, the domain wall DW moves within the third magnetization region A3 and does not invade the first magnetization region A1 or the second magnetization region A2.

[0036] 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 passing 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 By reversing the direction, the domain wall DW moves in the +x direction.

[0037] 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.

[0038] 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 the antiferromagnetic material include a laminated film of B (0≦x≦1) and the same material as the non-magnetic 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 small saturation magnetization, and the threshold current required to move the domain wall DW is small. Furthermore, a laminated film of Co and Ni, a laminated film of Co and Pt, and a laminated film of Co and Pd have large coercive force, and the moving speed of the domain wall DW is slow. Examples of the antiferromagnetic material include Mn ３ X (X is Sn, Ge, Ga, Pt, Ir, etc.), CuMnAs, Mn２ Au or the like can be used for the first ferromagnetic layer 10. The same material as the second ferromagnetic layer 30 described later can also be used for the first ferromagnetic layer 10. A laminated film or material of two or more types can also be used.

[0039] The nonmagnetic layer 20 is sandwiched between the first ferromagnetic layer 10 and the second ferromagnetic layer 30. 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.

[0040] The non-magnetic layer 20 is made of, for example, a non-magnetic insulator, a semiconductor, or a metal. The non-magnetic layer 20 is preferably made of, for example, a non-magnetic insulator. The non-magnetic insulator is, for example, Al. ２ O ３ , SiO ２ , MgO, MgAl ２ O ４ , and materials in which part of the Al, Si, and Mg in these are substituted with Zn, Be, Ga, Ti, etc. These materials have a large band gap and excellent insulating properties. The nonmagnetic insulator is, for example, an oxide containing Mg or Al. When the nonmagnetic layer 20 is made of a nonmagnetic insulator, the nonmagnetic layer 20 is a tunnel barrier layer. The nonmagnetic metal is, for example, Cu, Au, Ag, etc. The nonmagnetic semiconductor is, for example, Si, Ge, CuInSe ２ , CuGaSe ２ , Cu(In,Ga)Se ２ etc.

[0041] The thickness of the nonmagnetic layer 20 is, for example, 20 Å or more, and may be 25 Å or more.

[0042] The second ferromagnetic layer 30 sandwiches the nonmagnetic layer 20 together 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.

[0043] 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. ３０The second ferromagnetic layer 30 is fixed and does not change its direction when an external force is applied strong enough to reverse the magnetization of the third magnetization region A3. The second ferromagnetic layer 30 may also be called a fixed layer or a reference layer.

[0044] The second ferromagnetic layer 30 includes a ferromagnetic material. The second ferromagnetic layer 30 includes, for example, a material that easily achieves 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. Furthermore, a laminated film of Co and Ni, a laminated film of Co and Pt, or a laminated film of Co and Pd may be used as part of the second ferromagnetic layer 30.

[0045] 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 either XYZ or X ２ It is an intermetallic compound having a chemical composition of YZ, 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. ２ FeSi, Co ２ FeGe, Co ２ FeGa, Co ２ MnSi, Co ２ Mn １－ａ Fe ａ Al ｂ Si １－ｂ , Co ２ FeGe １－ｃ Ga ｃ etc.

[0046] The second ferromagnetic layer 30 may have multiple layers and may have a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure is composed 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.

[0047] 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 across the non-magnetic layer 20 is responsible for the resistance change of the domain wall motion element 100. If the length of the second ferromagnetic layer 30 and the non-magnetic layer 20 in the x direction is longer than the length of the third region in the x direction, it becomes easier to divide the resistance change width of the domain wall motion element 100 into more values.

[0048] 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.

[0049] The first magnetization fixed layer 40 is connected to the first ferromagnetic layer 10. The first magnetization fixed layer 40 is an example of a first magnetization fixed portion. The first magnetization fixed layer 40 is connected to the first magnetization region A1 of the first ferromagnetic layer 10. The magnetization M of the first magnetization fixed layer 40 ４０ pins the magnetization of the first magnetization region A1.

[0050] The first magnetization fixed layer 40 is, for example, a ferromagnetic material. For example, the same material as the first ferromagnetic layer 10 or the second ferromagnetic layer 30 can be used for the first magnetization fixed layer 40. The first magnetization fixed layer 40 may have multiple layers. For example, the first magnetization fixed layer 40 may have a stacked structure of multiple layers, and may include a mask layer, a cap layer, etc. formed during manufacturing.

[0051] The first magnetization pinned layer 40 may have a plurality of layers and may have a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure is composed of two magnetic layers sandwiching a nonmagnetic spacer layer. The magnetic layers include, for example, a ferromagnetic material and may also include an antiferromagnetic material such as IrMn or PtMn. The spacer layer includes, for example, at least one selected from the group consisting of Ru, Ir, and Rh.

[0052] Furthermore, the first magnetization pinned layer 40 is not limited to a ferromagnetic material. If the first magnetization pinned layer 40 is not a ferromagnetic material, the current density of the current flowing through the first ferromagnetic layer 10 changes suddenly in the region overlapping with the first magnetization pinned layer 40, thereby restricting the movement of the domain wall DW and pinning the magnetization of the first magnetization region A1.

[0053] The second magnetization pinned layer 50 is connected to the first ferromagnetic layer 10 at a position spaced apart from the first magnetization pinned layer 40 in the x-direction. The second magnetization pinned layer 50 is an example of a second magnetization pinned section. The second magnetization pinned layer 50 is connected to the second magnetization region A2 of the first ferromagnetic layer 10. The magnetization M of the second magnetization pinned layer 50 ５０ pins the magnetization of the second magnetization region A2.

[0054] The second magnetization pinned layer 50 may be made of the same material as the first magnetization pinned layer 40. The second magnetization pinned layer 50 may have a synthetic antiferromagnetic structure (SAF structure). The second magnetization pinned layer 50 may have multiple layers. For example, the second magnetization pinned layer 50 may have a stacked structure of multiple layers, and may include a mask layer, a cap layer, etc. formed during manufacturing.

[0055] The film thickness of the first magnetization pinned layer 40 and the film thickness of the second magnetization pinned layer 50 may be the same or different. For example, the film thickness of the first magnetization pinned layer 40 is thicker than the film thickness of the second magnetization pinned layer 50. If the film thickness of the first magnetization pinned layer 40 and the film thickness of the second magnetization pinned layer 50 are different, a difference in coercivity between the first magnetization pinned layer 40 and the second magnetization pinned layer 50 is likely to occur. If there is a difference in coercivity between the first magnetization pinned layer 40 and the second magnetization pinned layer 50, the magnetization M of the first magnetization pinned layer 40 may be increased at the time of manufacturing. ４０ and the magnetization M of the second magnetization fixed layer 50 ５０ This makes it easier to set the orientation direction of the film in a direction different from that of the film.

[0056] The second magnetization pinned layer 50 may also have a first layer 55 and a second layer 56. That is, the second magnetization pinned layer 50 may have a two-layer structure. The first layer 55 is closer to the first ferromagnetic layer 10 than the second layer 56. The first layer 55 and the second layer 56 are made of different materials. The first layer 55 includes, for example, the same material as the first magnetization pinned layer 40. The second layer 56 is a remaining portion of a mask layer 95, which will be described later. The second layer 56 may be made of, for example, Al, Cu, Ta, Ti, Zr, NiCr, nitrides (for example, TiN, TaN, SiN), oxides (for example, SiO ２ )

[0057] The position of the interface between the first layer 55 and the second layer 56 is arbitrary. For example, the position in the z direction of the interface between the first layer 55 and the second layer 56 may be the same as the position in the z direction of the upper surface (second surface 42) of the first magnetization fixed layer 40.

[0058] Here, the positional relationship between the first magnetization pinned layer 40 and the second magnetization pinned layer 50 is not limited to the example shown in Fig. 4. The positional relationship between the first magnetization pinned layer 40 and the second magnetization pinned layer 50 may be reversed, and the first magnetization pinned layer 40 may be located in the +x direction of the second magnetization pinned layer 50.

[0059] The first electrode 60 is connected to the first magnetization fixed layer 40. The first electrode 60 may be in direct contact with the first magnetization fixed layer 40, or may be indirectly connected via a layer in between. The first electrode 60 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 60 and the second electrode 70. The first electrode 60 includes a conductive material.

[0060] The second electrode 70 is connected to the second magnetization fixed layer 50. The second electrode 70 may be in direct contact with the second magnetization fixed layer 50, or may be indirectly connected via a layer in between. The second electrode 70 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 70 includes a conductive material.

[0061] The third electrode 80 is connected to the second ferromagnetic layer 30. The third electrode 80 may be in direct contact with the second ferromagnetic layer 30, or may be indirectly connected via a layer in between. The third electrode 80 is a read electrode used when applying a read current to the domain wall motion element 100. The third electrode 80 includes a conductive material.

[0062] The center C1 of the first electrode 60 in the x direction is located farther from the center C3 of the first ferromagnetic layer 10 in the x direction than the center C2 of the first magnetization fixed layer 40 in the x direction. If the yz planes passing through the centers C1, C2, and C3 are defined as imaginary planes P1, P2, and P3, respectively, the imaginary plane P1 is located farther from the imaginary plane P3 in the x direction than the imaginary plane P2.

[0063] Similarly, the center C4 of the second electrode 70 in the x direction is located farther from the center C3 of the first ferromagnetic layer 10 in the x direction than the center C5 of the second magnetization fixed layer 50 in the x direction. If the yz planes passing through the centers C1, C4, and C5 are defined as imaginary planes P1, P4, and P5, respectively, the imaginary plane P4 is located farther from the imaginary plane P3 in the x direction than the imaginary plane P5.

[0064] In the example shown in Figure 5, the centers C1, C2, C4, and C5 in the y direction of the first magnetization fixed layer 40, the second magnetization fixed layer 50, the first electrode 60, and the second electrode 70 are at the same position in the y direction and on the same imaginary plane P6.

[0065] 6 is an enlarged view of the vicinity of the first magnetization pinned layer 40 of the domain wall motion element 100 according to the first embodiment. The first magnetization pinned layer 40 has a first surface 41, a second surface 42, a first side surface 43, and a second side surface 44.

[0066] The first surface 41 is a surface on the first ferromagnetic layer 10 side and is in direct or indirect contact with the first ferromagnetic layer 10. The second surface 42 is a surface facing the first surface 41. The first side surface 43 is a side surface located on the outer side of the domain wall motion element 100. The second side surface 44 is a side surface located on the second magnetization fixed layer 50 side.

[0067] The second surface 42 has a connection surface 421 that contacts the first electrode 60 and a non-connection surface 422 that does not contact the first electrode 60. In other words, at least a portion of the second surface 42 does not contact the first electrode 60.

[0068] The first side surface 43 may be located, for example, closer to the inside of the domain wall motion element 100 than the first side surface 63 of the first electrode 60. That is, the first side surface 43 may be located closer to the imaginary plane P3 than the first side surface 63. The first side surface 63 is a side surface of the first electrode 60 located on the outside of the domain wall motion element 100, and the second side surface 64 is a side surface of the first electrode 60 located on the second magnetization fixed layer 50 side.

[0069] Furthermore, the second side surface 44 is, for example, located closer to the inside of the domain wall motion element 100 than the second side surface 64 of the first electrode 60. That is, the second side surface 44 may be located closer to the imaginary plane P3 than the second side surface 64. In this case, the first electrode 60 does not overlap with the third magnetization region A3 of the first ferromagnetic layer 10 in the z direction.

[0070] 7 is an enlarged view of the vicinity of the second magnetization fixed layer 50 of the domain wall motion element 100 according to the first embodiment. The second magnetization fixed layer 50 has a first surface 51, a second surface 52, a first side surface 53, and a second side surface 54.

[0071] The first surface 51 is a surface on the first ferromagnetic layer 10 side and is in direct or indirect contact with the first ferromagnetic layer 10. The second surface 52 is a surface facing the first surface 51. The first side surface 53 is a side surface located on the outer side of the domain wall motion element 100. The second side surface 54 is a side surface located on the first magnetization fixed layer 40 side.

[0072] The second surface 52 has a connection surface 521 that contacts the second electrode 70 and a non-connection surface 522 that does not contact the second electrode 70. In other words, at least a portion of the second surface 52 does not contact the second electrode 70.

[0073] The first side surface 53 may be located, for example, closer to the inside of the domain wall motion element 100 than the first side surface 73 of the second electrode 70. That is, the first side surface 53 may be located closer to the imaginary plane P3 than the first side surface 73. The first side surface 73 is a side surface of the second electrode 70 located on the outside of the domain wall motion element 100, and the second side surface 74 is a side surface of the second electrode 70 located on the first magnetization fixed layer 40 side.

[0074] Furthermore, the second side surface 54 is, for example, located closer to the inside of the domain wall motion element 100 than the second side surface 74 of the second electrode 70. That is, the second side surface 54 may be located closer to the imaginary plane P3 than the second side surface 74. In this case, the second electrode 70 does not overlap with the third magnetization region A3 of the first ferromagnetic layer 10 in the z direction.

[0075] 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). Also, an underlayer may be provided on the surface of the magnetic layer opposite the spacer layer.

[0076] The magnetization direction of each layer of the domain wall motion element 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 that uses the magneto-optical effect (magnetic Kerr effect) in which linearly polarized light is incident on a measurement object and the polarization direction rotates.

[0077] The domain wall motion element 100 is formed by a lamination process of each layer and a processing process of processing a part of each layer into a predetermined shape. Figures 8 to 12 are cross-sectional views for explaining a manufacturing method of the domain wall motion element 100 according to the first embodiment.

[0078] 8, in the first step, a ferromagnetic layer 91, a non-magnetic layer 92, a ferromagnetic layer 93, and a ferromagnetic layer 94 are sequentially stacked on an insulating layer 90 including a third electrode 80. The layers can be stacked by sputtering, chemical vapor deposition (CVD), electron beam evaporation (EB evaporation), atomic laser deposition, or the like.

[0079] Next, as shown in FIG. 9 , the stacked laminate is processed to match the outer shapes of the first ferromagnetic layer 10, the non-magnetic layer 20, and the second ferromagnetic layer 30. The laminate can be processed using photolithography, etching (e.g., Ar etching), or the like. The ferromagnetic layer 91 becomes the second ferromagnetic layer 30, the non-magnetic layer 92 becomes the non-magnetic layer 20, the ferromagnetic layer 93 becomes the first ferromagnetic layer 10, and the ferromagnetic layer 94 becomes the ferromagnetic layer 94A. Then, a mask layer 95 is formed at a predetermined position on the ferromagnetic layer 94A. The mask layer 95 can be made of, for example, Al, Cu, Ta, Ti, Zr, NiCr, nitrides (e.g., TiN, TaN, SiN), or oxides (e.g., SiO ２ )

[0080] 10, in a second step, the ferromagnetic layer 94A is processed using the mask layer 95 as a mask, so that the ferromagnetic layer 94A becomes two ferromagnetic layers 94B and 94C that are spaced apart from each other.

[0081] Next, the mask layer 95 on the ferromagnetic layer 94C is etched until the ferromagnetic layer 94C is exposed. At this time, a portion of the ferromagnetic layer 94C may also be etched. The etched ferromagnetic layer 94C becomes the first magnetization fixed layer 40. The ferromagnetic layer 94B and the mask layer 95 each become the second magnetization fixed layer 50 consisting of a first layer 55 and a second layer 56. Then, as shown in FIG. 11 , an insulating layer 90 is formed so as to fill the first magnetization fixed layer 40 and the second magnetization fixed layer 50. Then, a resist 96 having openings H1 and H2 formed therein is formed on the insulating layer 90.

[0082] Next, in the third and fourth steps, the first electrode 60 and the second electrode 70 are fabricated. The first electrode 60 and the second electrode 70 are obtained by filling the openings H3 and H4 with a conductor, as shown in FIG.

[0083] 12 , openings H3 and H4 are formed in the insulating layer 90 using openings H1 and H2 in the resist 96. The opening H3 is formed to satisfy a first condition and a second condition. The first condition is that the center of the first electrode 60 is located outside the center of the first magnetization fixed layer 40 in the x direction. The second condition is that at least a portion of the second surface 42 of the first magnetization fixed layer 40 is not in contact with the first electrode 60.

[0084] For example, the opening H3 is formed so that the center C1' in the x direction of the opening H3 is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C2 in the x direction of the first magnetization fixed layer 40. The opening H4 is formed so that the center C4' in the x direction of the opening H4 is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C4 in the x direction of the second magnetization fixed layer 50. After the openings H3 and H4 are formed, the resist 96 is removed.

[0085] When the center C1' is positioned outside the center C2, the overlapping portion of the third magnetization region A3 of the first ferromagnetic layer 10 and the opening H3 in the z direction can be reduced. When the opening H3 and the first ferromagnetic layer 10 overlap in the z direction, the thickness h of the insulating layer 90 between the opening H3 and the first ferromagnetic layer 10 is thinner than the thickness of the insulating layer 90 in other portions. When the opening H3 and the first ferromagnetic layer 10 overlap in the z direction, the energy used to process the opening H3 is applied to the insulating layer 90 with this thickness h. If the thickness h is small, part of that energy is applied to the first ferromagnetic layer 10, disrupting the magnetization stability of the first ferromagnetic layer 10. Furthermore, if the thickness h is small, part of the opening H3 may reach the first ferromagnetic layer 10. If the opening H3 reaches the first ferromagnetic layer 10, the first electrode 60 and the first ferromagnetic layer 10 are short-circuited. The domain wall DW still moves even if the first electrode 60 and the first ferromagnetic layer 10 are short-circuited. However, current components that do not pass through the first magnetization fixed layer 40 cannot move the domain wall DW, which reduces the operating efficiency of the domain wall motion element 100. If the center C1' is located outside the center C2, the position where the opening H3 is formed is shifted, and the portion where the thickness of the insulating layer 90 is thin can be reduced.

[0086] Similarly, when the center C4' is located outside the center C5, the overlapping portion between the third region of the first ferromagnetic layer 10 and the opening H4 in the z direction can be reduced. When the opening H4 and the first ferromagnetic layer 10 overlap in the z direction, energy is applied to the insulating layer 90 with a thickness h' between the opening H4 and the first ferromagnetic layer 10. If the thickness h' is small, part of that energy is applied to the first ferromagnetic layer 10, disrupting the magnetization stability of the first ferromagnetic layer 10. Furthermore, if the thickness h' is small, part of the opening H4 may reach the first ferromagnetic layer 10. If the opening H4 reaches the first ferromagnetic layer 10, the second electrode 70 and the first ferromagnetic layer 10 are short-circuited, reducing the operational efficiency of the domain wall DW. When the center C4' is located outside the center C5, the position where the opening H4 is formed is shifted, and the thin portion of the insulating layer 90 can be reduced.

[0087] Next, the openings H3 and H4 are filled with a conductor. The conductor filled in the opening H3 becomes the first electrode 60, and the conductor filled in the opening H4 becomes the second electrode 70. The first electrode 60 satisfies the first and second conditions.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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 layer 40 and the second magnetization pinned layer 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.

[0093] 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.

[0094] 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 an 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.

[0095] 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.

[0096] 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 layer 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.

[0097] 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. In this manner, a signal can be read out from a specific domain wall motion element 100.

[0098] According to the domain wall motion element 100 of this embodiment, the area where the insulating layer 90 is thin can be narrowed between the opening H3 or opening H4 ( FIG. 12 ) and the first ferromagnetic layer 10. This reduces processing damage to the first ferromagnetic layer 10 when forming the openings H3 and H4. Processing damage to the first ferromagnetic layer 10 inhibits stable operation of the domain wall DW and contributes to reduced reliability of the domain wall motion element 100. Therefore, the domain wall motion element 100 of this embodiment has excellent operational stability and high reliability.

[0099] Furthermore, a write current to the domain wall motion element 100 flows, for example, through the first electrode 60, the first magnetization pinned layer 40, the first ferromagnetic layer 10, the second magnetization pinned layer 50, and the second electrode 70 in this order. The write current flows in the z direction in the first electrode 60 and the second electrode 70. This write current flowing in the z direction generates a magnetic field around them. When the center C1 of the first electrode 60 is located outside the center C2 of the first magnetization pinned layer 40, the distance between the first electrode 60 and the third magnetization region A3 of the first ferromagnetic layer 10, where the domain wall DW moves, is longer than when the centers C1 and C2 are aligned in the x direction. Therefore, the magnetic field generated by the write current flowing through the first electrode 60 has a smaller effect on the domain wall DW. Similarly, when the center C4 of the second electrode 70 is located outside the center C5 of the second magnetization pinned layer 50, the magnetic field generated by the write current flowing through the second electrode 70 has a smaller effect on the domain wall DW. As a result, the domain wall motion element 100 according to this embodiment has excellent operational stability.

[0100] The domain wall motion element 100 according to the first embodiment can be used in, for example, a magnetic memory or a neuromorphic device.

[0101] 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.

[0102] In the case of a neuromorphic device, each of the domain wall motion elements 100 functions as a product operation 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.

[0103] 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.

[0104] 13 is a schematic diagram of the neural network NN. The neural network NN has an input layer L ｉｎ and the middle layer L ｍ and the output layer L ｏｕｔIn FIG. 13, the intermediate layer L ｍ presents an example of three layers, but the middle layer L ｍ The number of input layers L ｉｎ and the middle layer L ｍ and the output layer L ｏｕｔ Each of the input layers L has a plurality of chips C, each of which corresponds to a neuron in the brain. ｉｎ and the middle layer L ｍ and the output layer L ｏｕｔ The chips C and the number of transmission means shown in FIG. 13 are merely examples.

[0105] The neural network NN increases the rate of correct answers to questions as its transmission means (synapses) learn. Learning is the process of finding knowledge that may be useful in the future from information. The neural network NN learns by operating while changing the weight of the 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.

[0106] 14 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.

[0107] 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, the input layer L ｉｎ corresponds to the signal input to

[0108] 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.

[0109] 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.

[0110] The domain wall motion element 100 functions as a product calculation element because it outputs a signal that is the product of the input voltage and the conductance (or resistance) of the domain wall motion element 100 itself. 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.

[0111] 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.

[0112] 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 as to correspond to the weights 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.

[0113] 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.

[0114] The domain wall motion element 100 according to this embodiment has excellent operational stability, and therefore the reliability of the system 300 is high.

[0115] Second Embodiment Fig. 15 is a cross-sectional view of a domain wall motion element 101 according to a second embodiment. Fig. 15 is a cross-sectional view of the domain wall motion element 101 cut along an xz plane passing through the center of the first ferromagnetic layer 10 in the y direction. The domain wall motion element 101 can be replaced with the domain wall motion element 100. In the domain wall motion element 101, components similar to those in the domain wall motion element 100 are designated by similar reference numerals, and descriptions thereof will be omitted.

[0116] The domain wall motion element 101 has a first ferromagnetic layer 10, a non-magnetic layer 20, a second ferromagnetic layer 30, a first magnetization pinned layer 40A, a second magnetization pinned layer 50A, a first electrode 60A, and a second electrode 70A. The first magnetization pinned layer 40A, the second magnetization pinned layer 50A, the first electrode 60A, and the second electrode 70A differ from the first magnetization pinned layer 40, the second magnetization pinned layer 50, the first electrode 60, and the second electrode 70 in terms of their shapes or the state of connection with other layers, but are otherwise similar in configuration.

[0117] The center C1 in the x direction of the first electrode 60A is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C2 in the x direction of the first magnetization fixed layer 40A. The center C4 in the x direction of the second electrode 70A is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C5 in the x direction of the second magnetization fixed layer 50A.

[0118] 16 is an enlarged view of the vicinity of the first magnetization pinned layer 40A of the domain wall motion element 101 according to the second embodiment. The first magnetization pinned layer 40A has a first surface 41, a second surface 42A, a first side surface 43A, and a second side surface 44.

[0119] The second surface 42A is a surface facing the first surface 41. The second surface 42A has a connection surface 423 that contacts the first electrode 60A and a non-connection surface 424 that does not contact the first electrode 60A. In other words, at least a portion of the second surface 42A does not contact the first electrode 60A.

[0120] The connection surface 423 is closer to the first ferromagnetic layer 10 than the non-connection surface 424. The connection surface 423 is positioned differently in the z direction from the non-connection surface 424. This configuration is achieved by forming an opening that penetrates into a part of the first magnetization fixed layer 40A and filling the opening with a conductor. The first electrode 60A fits into a step formed in the first magnetization fixed layer 40A.

[0121] The first side surface 43A is a side surface located on the outside of the domain wall motion element 101. The first side surface 43A has a connection surface 431 that contacts the first electrode 60A and a non-connection surface 432 that does not contact the first electrode 60A. The first electrode 60A contacts the side surface of the first magnetization fixed layer 40A. The connection surface 431 is closer to the center C3 than the non-connection surface 432 and is located inside the domain wall motion element 101. The connection surface 431 is located at a different position in the x direction from the non-connection surface 432.

[0122] 17 is an enlarged view of the vicinity of the second magnetization fixed layer 50A of the domain wall motion element 101 according to the second embodiment. The second magnetization fixed layer 50A has a first surface 51, a second surface 52A, a first side surface 53A, and a second side surface 54.

[0123] The second surface 52A is a surface facing the first surface 51. The second surface 52A has a connection surface 523 that contacts the second electrode 70A and a non-connection surface 524 that does not contact the second electrode 70A. In other words, at least a portion of the second surface 52A does not contact the second electrode 70A.

[0124] The connection surface 523 is closer to the first ferromagnetic layer 10 than the non-connection surface 524. The connection surface 523 is positioned differently in the z direction from the non-connection surface 524. This configuration is achieved by forming an opening that penetrates into a part of the second magnetization fixed layer 50A and filling the opening with a conductor. The second electrode 70A fits into a step formed in the second magnetization fixed layer 50A.

[0125] The first side surface 53A is a side surface located on the outside of the domain wall motion element 101. The first side surface 53A has a connection surface 531 that contacts the second electrode 70A and a non-connection surface 532 that does not contact the second electrode 70A. The second electrode 70A contacts the side surface of the second magnetization fixed layer 50A. The connection surface 531 is closer to the center C3 than the non-connection surface 532 and is located inside the domain wall motion element 101. The connection surface 531 is located at a different position in the x direction from the non-connection surface 532.

[0126] In the second magnetization fixed layer 50, the position of the boundary surface between the first layer 55 and the second layer 56 may be the same as or different from the connection surface 523 (the bottom surface of the second electrode 70A).

[0127] In the domain wall motion element 101 according to the second embodiment, the central axes of the first electrode 60A and the first magnetization pinned layer 40A are misaligned, and the central axes of the second electrode 70A and the second magnetization pinned layer 50A are misaligned, so there is little risk of processing damage to the first ferromagnetic layer 10 during manufacturing. Furthermore, by achieving this configuration, it is possible to reduce the interference of the magnetic field generated by the write current with the motion of the domain wall DW. Therefore, the domain wall motion element 101 according to the second embodiment can achieve the same effects as the domain wall motion element 100 according to the first embodiment.

[0128] 18 is a cross-sectional view of a domain wall motion element 102 according to a third embodiment. Fig. 18 is a cross-sectional view of the domain wall motion element 102 cut along an xz plane passing through the center of the first ferromagnetic layer 10 in the y direction. The domain wall motion element 102 can be replaced with the domain wall motion element 100. In the domain wall motion element 102, the same components as those in the domain wall motion element 100 are denoted by the same reference numerals, and a description thereof will be omitted.

[0129] The domain wall motion element 102 has a first ferromagnetic layer 10B, a non-magnetic layer 20, a second ferromagnetic layer 30, a first magnetization pinned layer 40B, a second magnetization pinned layer 50B, a first electrode 60B, and a second electrode 70B. The first ferromagnetic layer 10B, the first magnetization pinned layer 40B, the second magnetization pinned layer 50B, the first electrode 60B, and the second electrode 70B differ from the first ferromagnetic layer 10, the first magnetization pinned layer 40, the second magnetization pinned layer 50, the first electrode 60, and the second electrode 70 in terms of their shapes or the state of connection with other layers, but are otherwise similar in configuration.

[0130] The center C1 of the first electrode 60B in the x direction is located farther from the center C3 of the first ferromagnetic layer 10B in the x direction than the center C2 of the first magnetization fixed layer 40B in the x direction. The center C4 of the second electrode 70B in the x direction is located farther from the center C3 of the first ferromagnetic layer 10B in the x direction than the center C5 of the second magnetization fixed layer 50B in the x direction.

[0131] 19 is an enlarged view of the vicinity of the first magnetization pinned layer 40B of the domain wall motion element 102 according to the second embodiment. The first magnetization pinned layer 40B has a first surface 41, a second surface 42B, a first side surface 43B, and a second side surface 44.

[0132] The second surface 42B is a surface facing the first surface 41. The second surface 42B is not in contact with the first electrode 60B. The first side surface 43B is in contact with the first electrode 60B.

[0133] The first electrode 60B is in contact with the first magnetization fixed layer 40B and the first ferromagnetic layer 10B. The first electrode 60B is formed by forming an opening that spans the first magnetization fixed layer 40B and the first ferromagnetic layer 10B and then filling the opening with a conductor. The first electrode 60B fits into a step formed in the first ferromagnetic layer 10B.

[0134] The first side surface 13B of the first ferromagnetic layer 10B has a connection surface 131 that contacts the first electrode 60B and a non-connection surface 132 that does not contact the first electrode 60B. The connection surface 131 corresponds to a first boundary surface that intersects with the x-direction at the boundary between the first electrode 60B and the first ferromagnetic layer 10B. The connection surface 131 is located closer to the domain wall motion element 102 than the non-connection surface 132 and closer to the domain wall motion element 102 than the side surface of the nonmagnetic layer 20.

[0135] 20 is an enlarged view of the vicinity of the second magnetization fixed layer 50B of the domain wall motion element 102 according to the third embodiment. The second magnetization fixed layer 50B has a first surface 51, a second surface 52B, a first side surface 53B, and a second side surface 54.

[0136] The second surface 52B is a surface facing the first surface 51. The second surface 52B is not in contact with the second electrode 70B. The first side surface 53B is in contact with the second electrode 70B.

[0137] The second electrode 70B is in contact with the second magnetization fixed layer 50B and the first ferromagnetic layer 10B. The second electrode 70B is formed by forming an opening that extends over the second magnetization fixed layer 50B and the first ferromagnetic layer 10B and then filling the opening with a conductor. The second electrode 70B fits into a step formed in the first ferromagnetic layer 10B.

[0138] The second side surface 14B of the first ferromagnetic layer 10B has a connection surface 141 that contacts the second electrode 70B and a non-connection surface 142 that does not contact the second electrode 70B. The connection surface 141 corresponds to a first boundary surface that intersects with the x-direction at the boundary between the second electrode 70B and the first ferromagnetic layer 10B. The connection surface 141 is located closer to the domain wall motion element 102 than the non-connection surface 142 and closer to the domain wall motion element 102 than the side surface of the nonmagnetic layer 20.

[0139] In the domain wall motion element 102 according to the third embodiment, the central axes of the first electrode 60B and the first magnetization pinned layer 40B are misaligned, and the central axes of the second electrode 70B and the second magnetization pinned layer 50B are misaligned, so there is little risk of processing damage to the first ferromagnetic layer 10B during manufacturing. Furthermore, by achieving this configuration, it is possible to reduce the interference of the magnetic field generated by the write current with the motion of the domain wall DW. Therefore, the domain wall motion element 102 according to the third embodiment can achieve the same effects as the domain wall motion element 100 according to the first embodiment.

[0140] 21 is a cross-sectional view of a domain wall motion element 103 according to a fourth embodiment. Fig. 21 is a cross-sectional view of the domain wall motion element 103 cut along an xz plane passing through the center of the first ferromagnetic layer 10 in the y direction. The domain wall motion element 103 can be replaced with the domain wall motion element 100. In the domain wall motion element 103, the same components as those in the domain wall motion element 100 are denoted by the same reference numerals, and description thereof will be omitted.

[0141] The domain wall motion element 103 has a first ferromagnetic layer 10, a non-magnetic layer 20, a second ferromagnetic layer 30, a first magnetization pinned layer 40, a second magnetization pinned layer 50, a first electrode 60C, and a second electrode 70C. The first electrode 60C and the second electrode 70C differ from the first electrode 60 and the second electrode 70 in that they have different shapes or different connections with other layers, but are otherwise similar in configuration.

[0142] The center C1 in the x direction of the first electrode 60C is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C2 in the x direction of the first magnetization fixed layer 40. The center C4 in the x direction of the second electrode 70C is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C5 in the x direction of the second magnetization fixed layer 50.

[0143] FIG. 22 is an enlarged view of the vicinity of the first magnetization fixed layer 40 of the domain wall motion element 103 according to the fourth embodiment.

[0144] At least a part of the second surface 42 of the first magnetization fixed layer 40 is not in contact with the first electrode 60C. The first electrode 60C is in contact with the second surface 42 and the first side surface 43 of the first magnetization fixed layer 40. The first electrode 60C has a part located in the −z direction from the second surface 42 of the first magnetization fixed layer 40.

[0145] FIG. 23 is an enlarged view of the vicinity of the second magnetization fixed layer 50 of the domain wall motion element 103 according to the fourth embodiment.

[0146] At least a part of the second surface 52 of the second magnetization fixed layer 50 is not in contact with the second electrode 70C. The second electrode 70C is in contact with the second surface 52 and the first side surface 53 of the second magnetization fixed layer 50. The second electrode 70C has a part located in the −z direction from the second surface 52 of the second magnetization fixed layer 50.

[0147] Like the domain wall motion device 100 according to the first embodiment, the domain wall motion device 103 according to the fourth embodiment has a low risk of causing processing damage to the first ferromagnetic layer 10 during manufacturing. Furthermore, by satisfying this configuration, it is possible to reduce the interference of the magnetic field generated by the write current with the motion of the domain wall DW.

[0148] Fifth Embodiment Fig. 24 is a cross-sectional view of a domain wall motion element 104 according to a fifth embodiment. Fig. 24 is a cross-sectional view of the domain wall motion element 104 cut along an xz plane passing through the center of the first ferromagnetic layer 10 in the y direction. The domain wall motion element 104 can be replaced with the domain wall motion element 100. In the domain wall motion element 104, the same components as those in the domain wall motion element 100 are denoted by the same reference numerals, and description thereof will be omitted.

[0149] The domain wall motion element 104 has a first ferromagnetic layer 10, a non-magnetic layer 20, a second ferromagnetic layer 30, a first magnetization pinned layer 40, a second magnetization pinned layer 50, a first electrode 60D, and a second electrode 70D. The first electrode 60D and the second electrode 70D differ from the first electrode 60 and the second electrode 70 in that they have different shapes or different connections with other layers, but are otherwise similar in configuration.

[0150] The center C1 in the x direction of the first electrode 60D is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C2 in the x direction of the first magnetization fixed layer 40. The center C4 in the x direction of the second electrode 70D is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C5 in the x direction of the second magnetization fixed layer 50.

[0151] FIG. 25 is an enlarged view of the vicinity of the first magnetization fixed layer 40 of the domain wall motion element 104 according to the fifth embodiment.

[0152] At least a part of the second surface 42 of the first magnetization fixed layer 40 is not in contact with the first electrode 60D. The first electrode 60D is in contact with the second surface 42 and the first side surface 43 of the first magnetization fixed layer 40. The first electrode 60D also contacts the side surface of the first ferromagnetic layer 10. The first electrode 60D has a portion located in the −z direction from the second surface 42 of the first magnetization fixed layer 40.

[0153] FIG. 26 is an enlarged view of the vicinity of the second magnetization fixed layer 50 of the domain wall motion element 104 according to the fifth embodiment.

[0154] At least a portion of the second surface 52 of the second magnetization fixed layer 50 is not in contact with the second electrode 70D. The second electrode 70D is in contact with the second surface 52 and the first side surface 53 of the second magnetization fixed layer 50. The second electrode 70D also contacts the side surface of the first ferromagnetic layer 10. The second electrode 70D has a portion located in the −z direction from the second surface 52 of the second magnetization fixed layer 50.

[0155] Like the domain wall motion device 100 according to the first embodiment, the domain wall motion device 104 according to the fifth embodiment has a low risk of causing processing damage to the first ferromagnetic layer 10 during manufacturing. Furthermore, by satisfying this configuration, it is possible to reduce the interference of the magnetic field generated by the write current with the motion of the domain wall DW.

[0156] 27 is a plan view of a domain wall motion element 105 according to a sixth embodiment. The domain wall motion element 105 can be replaced with the domain wall motion element 100. In the domain wall motion element 105, the same components as those in the domain wall motion element 100 are denoted by the same reference numerals, and description thereof will be omitted.

[0157] The domain wall motion element 105 has a first ferromagnetic layer 10, a non-magnetic layer 20, a second ferromagnetic layer 30, a first magnetization pinned layer 40, a second magnetization pinned layer 50, a first electrode 60E, and a second electrode 70E. The first electrode 60E and the second electrode 70E differ from the first electrode 60 and the second electrode 70, respectively, in that their positions in the y direction are different, but the rest of the configuration is similar.

[0158] The center C1 in the x direction of the first electrode 60E is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C2 in the x direction of the first magnetization fixed layer 40. The center C4 in the x direction of the second electrode 70E is located farther from the center C3 in the x direction of the first ferromagnetic layer 10 than the center C5 in the x direction of the second magnetization fixed layer 50.

[0159] The center C1 of the first electrode 60E in the y direction is shifted in the y direction from the center C2 of the first magnetization fixed layer 40 in the y direction and the center C3 of the first ferromagnetic layer 10 in the y direction. If the xz plane passing through the center C1 is defined as a virtual plane P7, and the xz plane passing through the center C3 is defined as a virtual plane P6, the virtual planes P7 and P6 are shifted in the y direction.

[0160] The center C4 of the second electrode 70E in the y direction is shifted in the y direction from the center C5 of the second magnetization fixed layer 50 in the y direction and the center C3 of the first ferromagnetic layer 10 in the y direction. If the xz plane passing through the center C4 is defined as a virtual plane P8 and the xz plane passing through the center C3 is defined as a virtual plane P6, the virtual planes P8 and P6 are shifted in the y direction.

[0161] In the example shown in Figure 27, both the first electrode 60E and the second electrode 70E are shifted in the +y direction relative to the first ferromagnetic layer 10, but both the first electrode 60E and the second electrode 70E may be shifted in the -y direction relative to the first ferromagnetic layer 10, or the first electrode 60E and the second electrode 70E may be shifted in different directions relative to the first ferromagnetic layer 10.

[0162] In the domain wall motion element 105 according to the sixth embodiment, the central axes of the first electrode 60E and the first magnetization pinned layer 40 are misaligned, and the central axes of the second electrode 70E and the second magnetization pinned layer 50B are misaligned, so there is little risk of processing damage to the first ferromagnetic layer 10 during manufacturing. Furthermore, because these central axes are also misaligned in the y direction, it is possible to further reduce the interference of the magnetic field generated by the write current with the motion of the domain wall DW. Therefore, the domain wall motion element 105 according to the sixth embodiment can achieve the same effects as the domain wall motion element 100 according to the first embodiment.

[0163] Seventh Embodiment Fig. 28 is a cross-sectional view of a domain wall motion element 106 according to a seventh embodiment. Fig. 28 is a cross-sectional view of the domain wall motion element 106 cut along an xz plane passing through the center of the first ferromagnetic layer 10 in the y direction. The domain wall motion element 106 can be replaced with the domain wall motion element 100. In the domain wall motion element 106, the same components as those in the domain wall motion element 100 are denoted by the same reference numerals, and description thereof will be omitted.

[0164] The domain wall motion element 106 has a first ferromagnetic layer 10, a non-magnetic layer 20, a second ferromagnetic layer 30, a first magnetization pinned layer 40, a second magnetization pinned layer 50, a first electrode 60F, a second electrode 70, and an intermediate layer 85. The first electrode 60F differs from the first electrode 60 in terms of its shape or the state of connection with other layers, but is otherwise similar in configuration.

[0165] The intermediate layer 85 is located between the first magnetization fixed layer 40 and the first electrode 60F. The first electrode 60F is in contact with the first magnetization fixed layer 40 via the intermediate layer 85. The intermediate layer 85 is made of a conductive material, such as a metal.

[0166] The intermediate layer 85 is formed after etching the mask layer 95 (see FIG. 10) to form the first magnetization pinned layer 40. The intermediate layer 85 is formed on the first magnetization pinned layer 40 so as to eliminate the difference in height between the first magnetization pinned layer 40 and the second magnetization pinned layer 50. When the height positions of the upper surface of the intermediate layer 85 and the upper surface of the second magnetization pinned layer 50 (the upper surface of the mask layer 95 in FIG. 11) are aligned, the depths of the openings H3 and H4 (see FIG. 12) become approximately equal. This makes it easy to simultaneously form the openings H3 and H4, thereby shortening the manufacturing process.

[0167] In the domain wall motion device 106 according to the seventh embodiment, the central axes of the first electrode 60F and the first magnetization pinned layer 40 are misaligned, and the central axes of the second electrode 70 and the second magnetization pinned layer 50B are misaligned, so there is little risk of processing damage to the first ferromagnetic layer 10 during manufacturing. Furthermore, by achieving this configuration, it is possible to reduce the interference of the magnetic field generated by the write current with the motion of the domain wall DW. Therefore, the domain wall motion device 106 according to the seventh embodiment can achieve the same effects as the domain wall motion device 100 according to the first embodiment.

[0168] Eighth Embodiment Fig. 29 is a cross-sectional view of a domain wall motion element 107 according to an eighth embodiment. Fig. 29 is a cross-sectional view of the domain wall motion element 107 cut along an xz plane passing through the center of the first ferromagnetic layer 10 in the y direction. The domain wall motion element 107 can be replaced with the domain wall motion element 100. In the domain wall motion element 107, the same components as those in the domain wall motion element 100 are denoted by the same reference numerals, and description thereof will be omitted.

[0169] The domain wall motion element 107 has a first ferromagnetic layer 10, a non-magnetic layer 20, a second ferromagnetic layer 30, a first magnetization pinned layer 40, a second magnetization pinned layer 50, a first electrode 60, and a second electrode 70G. The second electrode 70G differs from the second electrode 70 in terms of its shape or the state of connection with other layers, but is otherwise similar in configuration.

[0170] In the first to fifth embodiments, examples have been shown in which the central axes of the first electrode 60 and the first magnetization fixed layer 40 are misaligned and the central axes of the second electrode 70 and the second magnetization fixed layer 50 are misaligned, but a configuration in which only one of the central axes is misaligned is also possible. The domain wall motion element 105 is an example in which the central axes of the first electrode 60 and the first magnetization fixed layer 40 in the x direction are misaligned and the central axes of the second electrode 70G and the second magnetization fixed layer 50 in the x direction are aligned. The second magnetization fixed layer 50 is in contact with the second electrode 70E over the entire surface. Here, based on the configuration of the first embodiment, an example has been shown in which only the central axes of the first electrode 60 and the first magnetization fixed layer 40 in the x direction are misaligned, but a similar configuration can be selected for the configurations of the second to fifth embodiments.

[0171] 29 illustrates an example in which the x-direction central axes of the first electrode 60 and the first magnetization pinned layer 40 are misaligned and the x-direction central axes of the second electrode 70G and the second magnetization pinned layer 50 are aligned. However, the x-direction central axes of the first electrode 60 and the first magnetization pinned layer 40 may be aligned and the x-direction central axes of the second electrode 70G and the second magnetization pinned layer 50 may be misaligned. Since the first magnetization pinned layer 40 is thinner than the second magnetization pinned layer 50, it is preferable that the x-direction central axes of the first electrode 60 and the first magnetization pinned layer 40 are misaligned. As shown in FIG. 12 , the thickness h of the insulating layer 90 between the opening H3 and the first ferromagnetic layer 10 is thinner than the thickness h′ of the insulating layer 90 between the opening H4 and the first ferromagnetic layer 10. Therefore, misalignment of the central axes of the first electrode 60 and the first magnetization fixed layer 40 in the x direction reduces the risk of causing processing damage to the first ferromagnetic layer 10 when forming the opening H3.

[0172] In the domain wall motion device 107 according to the eighth embodiment, the central axes of the first electrode 60 and the first magnetization fixed layer 40 are misaligned, so there is little risk of processing damage to the first ferromagnetic layer 10 during manufacturing. Furthermore, by achieving this configuration, it is possible to reduce the interference of the magnetic field generated by the write current with the motion of the domain wall DW. Therefore, the domain wall motion device 107 according to the eighth embodiment can achieve the same effects as the domain wall motion device 100 according to the first embodiment.

[0173] Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to this embodiment. For example, characteristic configurations of the embodiments may be combined, or parts may be modified within the scope of the invention without departing from the spirit of the invention. For example, the configurations of the embodiments may be combined in which the structure near the first magnetization fixed part and the structure near the second magnetization fixed part are different.

[0174] REFERENCE SIGNS LIST 1 Integration region 2 Peripheral region 3 Control device 4 Resistance detection device 5 Output section 6 Control section 7 Power supply 10, 10B First ferromagnetic layer 20 Non-magnetic layer 30 Second ferromagnetic layer 40, 40A, 40B First magnetization fixed layer 50, 50A, 50B Second magnetization fixed layer 55 First layer 56 Second layer 60, 60A, 60B, 60C, 60D, 60E, 60F First electrode 70, 70A, 70B, 70C, 70D, 70E, 70G Second electrode 80 Third electrode 85 Intermediate layer 100, 101, 102, 103, 104, 105, 106, 107 Domain wall motion element 131, 141, 421, 423, 431, 521, 523, 531 Connecting surface 132, 142, 422, 424, 432, 522, 524, 532 Non-connecting surface 200 Neuromorphic device 201 Sensor 202 Communication unit 300 System C1, C1', C2, C3, C4, C4', C5 Center MA Magnetic array

Claims

1. A magnetic wall movement element comprising: a first ferromagnetic layer having a magnetic wall inside; a second ferromagnetic layer; a non-magnetic layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer; a first magnetization fixing portion connected to the first ferromagnetic layer; a second magnetization fixing portion connected to the first ferromagnetic layer at a position spaced apart from the first magnetization fixing portion in a first direction; a first electrode connected to the first magnetization fixing portion; and a second electrode connected to the second magnetization fixing portion, wherein the second ferromagnetic layer is closer to the substrate than the first ferromagnetic layer, in the first direction, the center of the first electrode is located at a position farther from the center of the first ferromagnetic layer than the center of the first magnetization fixing portion, the first magnetization fixing portion has a first surface in contact with the first ferromagnetic layer and a second surface facing the first surface, and at least a part of the second surface is not in contact with the first electrode.

2. The magnetic wall movement element according to claim 1, wherein a first connection surface of the second surface in contact with the first electrode is closer to the first ferromagnetic layer than a first non-connection surface of the second surface not in contact with the first electrode.

3. The magnetic wall movement element according to claim 1, wherein the first electrode is in contact with a side surface of the first magnetization fixing portion.

4. The magnetic wall movement element according to claim 1, wherein the first electrode is in contact with a side surface of the first ferromagnetic layer.

5. The magnetic wall movement element according to claim 4, wherein a first boundary surface of the boundary between the first electrode and the first ferromagnetic layer intersecting the first direction is closer to the center in the first direction of the first ferromagnetic layer than a first side surface of the non-magnetic layer.

6. The magnetic wall movement element according to claim 1, wherein a center position of the first electrode in a second direction orthogonal to the first direction when viewed in the stacking direction is different from a center position of the first ferromagnetic layer in the second direction.

7. The magnetic wall movement element according to claim 1, wherein the thickness of the first magnetization fixing portion is thinner than the thickness of the second magnetization fixing portion.

8. The magnetic wall movement element according to claim 7, further comprising an intermediate layer between the first magnetization fixing portion and the first electrode.

9. The magnetic wall movement element according to claim 1, wherein in the first direction, the center of the second electrode is located at a position farther from the center of the first ferromagnetic layer than the center of the second magnetization fixing portion.

10. The magnetic wall movement element according to claim 1, wherein the first magnetization fixing portion or the second magnetization fixing portion has a first layer and a second layer, and the first layer is closer to the first ferromagnetic layer than the second layer.

11. A magnetic array including the magnetic wall movement element according to claim 1.

12. A neuromorphic device including the magnetic wall movement element according to claim 1.

13. A method for manufacturing a magnetic wall movement element, comprising: a first step of laminating a laminate including a second ferromagnetic layer, a nonmagnetic layer, and a first ferromagnetic layer; a second step of forming a first magnetization fixing portion and a second magnetization fixing portion on one surface of the first ferromagnetic layer so as to be separated from each other; a third step of forming a first electrode in contact with the first magnetization fixing portion; and a fourth step of forming a second electrode in contact with the second magnetization fixing portion. In the third step, the first electrode is formed to satisfy a first condition and a second condition. The first condition is that in a first direction from the first magnetization fixing portion toward the second magnetization fixing portion, the center of the first electrode is located farther from the center of the first ferromagnetic layer than the center of the first magnetization fixing portion. The second condition is that at least a part of a second surface of the first magnetization fixing portion facing the first surface in contact with the first ferromagnetic layer does not contact the first electrode.

14. The method for manufacturing a magnetic wall movement element according to claim 13, wherein the second electrode is formed such that in the first direction, the center of the second electrode is located farther from the center of the first ferromagnetic layer than the center of the second magnetization fixing portion.

15. The method for manufacturing a magnetic wall movement element according to claim 13, wherein the third step includes a step of covering the periphery of the first magnetization fixing portion and the second magnetization fixing portion with an insulating layer, a step of forming a first opening in the insulating layer, and a step of filling the first opening with a conductor. The first opening is formed such that in the first direction, the center of the first opening is located farther from the center of the first ferromagnetic layer than the center of the second magnetization fixing portion.

16. The method for manufacturing a magnetic wall movement element according to claim 13, wherein the first magnetization fixing portion is thinner than the second magnetization fixing portion in the lamination direction.

17. The method for manufacturing a magnetic wall movement element according to claim 16, further comprising a step of forming an intermediate layer between the first magnetization fixing portion and the first electrode.

18. The second step includes a step of forming a ferromagnetic layer on one surface of the first ferromagnetic layer, a step of forming a mask layer covering a part of the ferromagnetic layer, a step of processing the ferromagnetic layer through the mask layer, and a step of removing a part of the mask layer. The method for manufacturing a magnetic domain wall motion element according to claim 13.

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