Domain wall motion element and magnetic array

Abstract

To provide a magnetic domain wall motion device having a large MR ratio and having the large number of bits of multilevel data recording, and a magnetic array.SOLUTION: A magnetic domain wall motion device 103 comprises a magnetoresistance effect portion 10 in which a reference layer 3, a domain wall motion layer 1 and a non-magnetic layer 2 positioned between the reference layer and the domain wall motion layer are laminated in a (x) direction. The domain wall motion layer includes: a first region A1 and a second region A2 which extend in a (y) direction orthogonal to the (x) direction and of which the magnetization direction is fixed; and a third region A3 which is located at a position interposed between the first region and the second region in the (y) direction and of which the magnetization direction is variable. The magnetic domain wall motion device further comprises: a first electrode 41 electrically connected to the first region; a second electrode 42 electrically connected to the second region; a third electrode 40A electrically connected to the reference layer; a first magnetization fixing layer 20 which is positions between the first region and the first electrode and fixes magnetization of the first region; and a second magnetization fixing layer 30 which is positioned between the second region and the second electrode and fixes magnetization of the second region.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a domain wall motion element and a magnetic array. [Background technology]

[0002] Attention is being focused on next-generation non-volatile memories to replace flash memories, etc., which are reaching the limits of miniaturization. For example, MRAM (Magnetoresistive Random Access Memory), ReRAM (Resistive Random Access Memory), PCRAM (Phase Change Random Access Memory), etc. are known as next-generation non-volatile memories.

[0003] MRAM uses the change in resistance caused by the change in the direction of magnetization to record data. In order to increase the capacity of recording memory, studies are being conducted on miniaturizing the elements that make up the memory and increasing the number of recording bits per element that makes up the memory.

[0004] Patent Document 1 describes a domain wall motion element that can change the resistance value by moving the domain wall and record multi-value or digital data. Patent Document 1 also describes that a data recording layer (domain wall motion layer) is provided with a domain wall motion region where the domain wall can move and a magnetization fixed region that limits the movement range of the domain wall. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-219104 A Summary of the Invention [Problem to be solved by the invention]

[0006] The domain wall motion element is often used in an integrated manner. In order to increase the integration of the domain wall motion element, it is preferable that the magnetization fixed regions provided at both ends of the domain wall motion layer overlap with the reference layer of the domain wall motion element. However, in such a structure, when reading the resistance value of the domain wall motion element, a current flows through a path that does not pass through the domain wall motion region, and the MR ratio, which is the ratio of the maximum resistance value to the minimum resistance value, decreases. If the MR ratio decreases, even if the domain wall position is finely controlled, the change in the resistance value cannot be detected, and the number of bits for multi-value data recording decreases.

[0007] The present invention has been made in view of the above problems, and has an object to provide a domain wall motion element and a magnetic array which have a large MR ratio and a large number of bits for multi-value data recording. [Means for solving the problem]

[0008] (1) A domain wall motion element according to a first aspect includes a magnetoresistive effect section in which a reference layer and a domain wall motion layer, each of which includes a ferromagnetic material, and a non-magnetic layer located between the reference layer and the domain wall motion layer are stacked in a first direction, the domain wall motion layer extending in a second direction perpendicular to the first direction, includes a first region whose magnetization direction is fixed, a second region whose magnetization direction is fixed in a direction different from the magnetization direction of the first region, and a third region whose magnetization direction is variable and is located between the first region and the second region in the second direction, and a first electrode electrically connected to the first region, and a second electrode electrically connected to the second region. and a third electrode located on the opposite side of the non-magnetic layer in the first direction with the reference layer as a reference and electrically connected to the reference layer, a first magnetization fixed layer located between the first region and the first electrode and fixing the magnetization of the first region, and a second magnetization fixed layer located between the second region and the second electrode and fixing the magnetization of the second region, the reference layer overlaps with at least a portion of the first region and the second region in a planar view from the first direction, and at least one of the first region and the second region has a portion that is shorter in length in a third direction perpendicular to the first direction and the second direction than the third region.

[0009] (2) The domain wall motion element according to the above aspect may further include a substrate on an opposite side to the reference layer with respect to the third electrode in the first direction.

[0010] (3) In the domain wall motion element according to the above aspect, at least one of the first region and the second region may have a length in the second direction longer than a length in the third direction.

[0011] (4) In the domain wall motion element according to the above aspect, at least one of the first region and the second region may have a first portion having a longer length in the third direction than the third region, and a second portion having a shorter length in the third direction than the third region, and the first portion may be located closer to the third region in the second direction than the second portion.

[0012] (5) In the domain wall motion element according to the above aspect, the length in the third direction of at least one of the first region and the second region may gradually decrease from an end portion adjacent to the third region toward an opposite end portion in the second direction.

[0013] (6) In the domain wall motion element according to the above aspect, the third region may have a thickness at its ends in the second direction that is thicker than a thickness at its central portion in the second direction, and the length in the third direction of the ends may be shorter than a length in the third direction of the central portion.

[0014] (7) In the domain wall motion element according to the above aspect, when viewed in a planar view from the first direction, the outer periphery of a first surface of the third electrode, which is the surface closest to the reference layer, may overlap with at least one of the first region and the second region.

[0015] (8) In the domain wall motion element according to the above aspect, a first surface of the third electrode, which is a surface closest to the reference layer in a plan view from the first direction, may overlap the entire domain wall motion layer.

[0016] (9) In the domain wall motion element according to the above aspect, a first surface of the third electrode, which is a surface closest to the reference layer, may have a length that is the longest part in the third direction shorter than a length that is the longest part in the second direction.

[0017] (10) In the domain wall motion element of the above aspect, the first magnetization fixed layer may have a thickness greater than that of the second magnetization fixed layer, and the distance from the geometric center of a first surface, which is the surface of the third electrode closest to the reference layer, to the first magnetization fixed layer in a planar view from the first direction may be shorter than the distance from the geometric center of the first surface to the second magnetization fixed layer.

[0018] (11) In the domain wall motion element according to the above aspect, in a planar view from the first direction, the entire first region may overlap with the first electrode, and the distance from the first region to an outer periphery of the first electrode may be shortest at a certain point.

[0019] (12) A magnetic array according to a second aspect includes a plurality of domain wall motion elements according to the above aspect. Effect of the Invention

[0020] The domain wall motion element and magnetic array according to the above aspect have a large MR ratio and can increase the number of bits for multi-value data recording. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a configuration diagram of a magnetic array according to a first embodiment. [Diagram 2] 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. [Diagram 3] 1 is a cross-sectional view of a domain wall motion element according to a first embodiment. [Figure 4] 1 is a plan view of a domain wall motion element according to a first embodiment. [Diagram 5] FIG. 11 is a plan view of a domain wall motion element according to a second embodiment. [Figure 6] FIG. 11 is a plan view of a domain wall motion element according to a third embodiment. [Figure 7] FIG. 11 is a cross-sectional view of a domain wall motion element according to a fourth embodiment. [Figure 8] FIG. 13 is a plan view of a domain wall motion element according to a fourth embodiment. [Figure 9] FIG. 13 is a plan view of a domain wall motion element according to a fifth embodiment. [Figure 10] FIG. 13 is a plan view of a domain wall motion element according to a sixth embodiment. [Figure 11] FIG. 13 is a cross-sectional view of a domain wall motion element according to a seventh embodiment. [Figure 12] FIG. 13 is a plan view of a domain wall motion element according to the seventh embodiment. [Figure 13] FIG. 13 is a plan view of a domain wall motion element according to an eighth embodiment. [Figure 14] FIG. 11 is a cross-sectional view of a domain wall motion element according to a first modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. They may be modified as appropriate within the scope of the effects of the present invention.

[0023] First, the directions are defined. The x and y directions are approximately parallel to one surface of the substrate Sub (see FIG. 2) described later. The x direction is the direction in which the domain wall motion layer 1 described later extends. The x direction is an example of a first direction. The y direction is a direction perpendicular to the x direction. The z direction is a direction from the substrate Sub described later to the domain wall motion element. 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.

[0024] [First embodiment] 1 is a configuration diagram of a magnetic array according to the first embodiment. The magnetic array 200 includes a plurality of domain wall motion elements 100, a plurality of first wirings WL, a plurality of second wirings CL, a plurality of third wirings RL, a plurality of first switching elements SW1, a plurality of second switching elements SW2, and a plurality of third switching elements SW3. The magnetic array 200 can be used, for example, in a magnetic memory, a multiply-accumulate calculator, a neuromorphic device, a spin memristor, and a magneto-optical element.

[0025] Each of the first wirings WL is a write wiring. Each of the first wirings WL electrically connects a power source to one or more of the domain wall motion elements 100. The power source is connected to one end of the magnetic array 200 during use.

[0026] Each of the second wirings CL is a common wiring. The common wiring is a wiring that can be used both when writing and reading data. Each of the second wirings CL electrically connects a reference potential to one or more domain wall motion elements 100. The reference potential is, for example, ground. The second wirings 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.

[0027] Each of the third wirings RL is a read wiring. Each of the third wirings RL electrically connects a power source to one or more of the domain wall motion elements 100. The power source is connected to one end of the magnetic array 200 during use.

[0028] 1, a first switching element SW1, a second switching element SW2, and a third switching element SW3 are connected to each of the multiple domain wall motion elements 100. The first switching element SW1 is connected between the domain wall motion element 100 and a first wiring WL. The second switching element SW2 is connected between the domain wall motion element 100 and a second wiring CL. The third switching element SW3 is connected between the domain wall motion element 100 and a third wiring RL.

[0029] When the first switching element SW1 and the second switching element SW2 are turned ON, a write current flows between the first wiring WL and the second wiring CL connected to a predetermined domain wall motion element 100. When the second switching element SW2 and the third switching element SW3 are turned ON, a read current flows between the second wiring CL and the third wiring RL connected to a predetermined domain wall motion element 100.

[0030] The first switching element SW1, the second switching element SW2, and the third switching element SW3 are elements that control the flow of current. The first switching element SW1, the second switching element SW2, and the third switching element SW3 are, 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 whose conductivity changes with a change in atomic position.

[0031] Any of the first switching element SW1, the second switching element SW2, and the third switching element SW3 may be shared by the domain wall motion elements 100 connected to the same wiring. For example, when the first switching element SW1 is shared, one first switching element SW1 is provided upstream (one end) of the first wiring WL. For example, when the second switching element SW2 is shared, one second switching element SW2 is provided upstream (one end) of the second wiring CL. For example, when the third switching element SW3 is shared, one third switching element SW3 is provided upstream (one end) of the third wiring RL.

[0032] Fig. 2 is a cross-sectional view of the vicinity of the domain wall motion element 100 of the magnetic array 200 according to the first embodiment. Fig. 2 is a cross-section of one domain wall motion element 100 in Fig. 1 cut along the xz plane passing through the center of the width of the domain wall motion layer 1 in the y direction.

[0033] The first switching element SW1 and the second switching element SW2 shown in FIG. 2 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 in a substrate Sub. The source S and the drain D are determined by the direction of current flow, and are both active regions. FIG. 2 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 switching element SW3 is electrically connected to the third wiring RL, and is, for example, shifted in the y direction in FIG. 2.

[0034] Each of the transistors Tr and the domain wall motion element 100 are electrically connected via wirings w1 and w2. The wirings w1 and w2 include a conductive material. The wiring w1 is a via wiring extending in the z direction. The wiring w2 is an in-plane wiring extending in any direction within the xy plane. The wirings w1 and w2 are formed within an opening in the insulating layer 90.

[0035] The insulating layer 90 is an insulating layer that insulates between wirings in a multilayer wiring structure and between elements. The insulating layer 90 is made of, for example, silicon oxide (SiO x ), silicon nitride (SiN x ), silicon carbide (SiC), chromium nitride (CrN), silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al 2 O 3 ), zirconium oxide (ZrO x ), magnesium oxide (MgO), etc.

[0036] Although FIG. 2 shows an example in which the domain wall motion element 100 is located above the substrate Sub with the insulating layer 90 interposed therebetween, the domain wall motion element 100 may be located on the substrate Sub.

[0037] "Magnetic domain wall motion element" Fig. 3 is a cross-sectional view of the domain wall motion element 100 cut in the xz plane passing through the center of the domain wall motion layer 1 in the y direction. Fig. 3 is a cross section taken along line AA in Fig. 4. Fig. 4 is a plan view of the domain wall motion element 100 as viewed from the z direction. Fig. 4 shows with dashed lines the first electrode 41, the second electrode 42, and the portions of the third electrode 40 that overlap with the magnetoresistance effect part 10. The arrows shown in the figure are an example of the orientation direction of magnetization of a ferromagnetic body.

[0038] The domain wall motion element 100 is, for example, a three-terminal element having a magnetoresistive effect part 10, a first magnetization pinned layer 20, a second magnetization pinned layer 30, a first electrode 41, a second electrode 42, and a third electrode 40. The periphery of the domain wall motion element 100 is covered with an insulating layer 90.

[0039] The magnetoresistance effect unit 10 includes a domain wall motion layer 1, a non-magnetic layer 2, and a reference layer 3. The domain wall motion element 100 includes, for example, a third electrode 40, a reference layer 3, a non-magnetic layer 2, a domain wall motion layer 1, a first magnetization pinned layer 20, a second magnetization pinned layer 30, a first electrode 41, and a second electrode 42, in this order from the side closer to the substrate Sub. When writing data to the magnetoresistance effect unit 10, a write current is passed along the domain wall motion layer 1. When reading data from the magnetoresistance effect element 10, a read current is passed between the third electrode 40 and the first electrode 41 or the second electrode 42, and a current is applied in the z direction of the magnetoresistance effect element 10.

[0040] The domain wall displacement layer 1 extends in the x-direction. The domain wall displacement layer 1 has multiple magnetic domains therein, and has a domain wall DW at the boundary between the multiple magnetic domains. The domain wall displacement layer 1 is, for example, a layer capable of magnetically recording multi-value data by changing the magnetic state. The domain wall displacement layer 1 may be called an analog layer or a magnetic recording layer.

[0041] The domain wall displacement layer 1 has a first region A1, a second region A2, and a third region A3. The first region A1 is, for example, a region from a first end of the domain wall displacement layer 1 in the x direction to a position where it overlaps with the element inner end of the first magnetization fixed layer 20. The second region A2 is, for example, a region from a second end on the opposite side to the first end of the domain wall displacement layer 1 in the x direction to a position where it overlaps with the element inner end of the second magnetization fixed layer 30. The third region A3 is a region sandwiched between the first region A1 and the second region A2 in the x direction.

[0042] Magnetization M of the first region A1 A1 is, for example, the magnetization M of the first magnetization fixed layer 20 20 The magnetization M of the second region A2 is fixed in the same direction. A2 is, for example, the magnetization M of the second magnetization fixed layer 30. 30 The magnetization is fixed in the same direction as the magnetization in the first region A1. The magnetization is fixed in the same direction as the magnetization in the first region A2. The magnetization is fixed in the same direction as the magnetization in the first region A3. The magnetization is fixed in the same direction as the magnetization in the first region A4. A1 and the magnetization M of the second region A2 A2 For example, the orientation direction is opposite to that of the above.

[0043] The third region A3 is a region where the direction of magnetization changes and the domain wall DW can move. The third region A3 has, for example, a substantially constant length in the y direction. The third region A3 has, for example, a thickness t C than the thickness t E The thickness of the third region A3 increases continuously from the center in the x direction toward the end in the x direction. The third region A3 has a first magnetic domain A3a and a second magnetic domain A3b. The magnetization M of the first magnetic domain A3a A3a and the magnetization M of the second magnetic domain A3b A3b For example, the orientation direction is opposite to that of the first magnetic domain A3a. The boundary between the first magnetic domain A3a and the second magnetic domain A3b is a domain wall DW. The magnetization M of the first magnetic domain A3a A3a For example, the magnetization M of the first region A1 A1 The magnetization M of the second magnetic domain A3b is oriented in the same direction. A3b For example, the magnetization M of the second region A2 A2The domain wall DW moves in the third region A3 in principle and does not invade the first region A1 or the second region A2.

[0044] As shown in FIG. 4, the length W A1 is the length W of the third region A3 in the y direction A3 The length in the x direction of each region is shorter than the length in the y direction of the lower surface of each region. Here, the length in the y direction of each region is the average of the length in the y direction of the lower surface of each region and the length in the y direction of the upper surface of each region. For example, the length in the x direction of the first region A1 is longer than the length in the y direction. For example, the boundary between the first region A1 and the third region A3 and the boundary between the second region A2 and the third region A3 are each approximately perpendicular to the x direction, which is the extension direction of the domain wall displacement layer 1.

[0045] When the volume ratio between the first magnetic domain A3a and the second magnetic domain A3b in the third region A3 changes, the domain wall DW moves. The domain wall DW moves by applying a write current in the x direction of the third region A3. For example, when a write current (e.g., a current pulse) in the +x direction is applied to the third region A3, electrons flow in the -x direction opposite to the current, and the domain wall DW moves in the -x direction. When a current flows from the first magnetic domain A3a to the second magnetic domain A3b, the spin-polarized electrons in the second magnetic domain A3b reverse the magnetization of the first magnetic domain A3a. When the magnetization of the first magnetic domain A3a is reversed, the domain wall DW moves in the -x direction.

[0046] When the volume ratio of the first magnetic domain A3a to the second magnetic domain A3b in the magnetic domain wall motion layer 1 changes, the resistance value of the magnetic domain wall motion element 100 changes. The resistance value of the magnetic domain wall motion element 100 changes according to the relative angle of the magnetizations of the ferromagnetic layers sandwiching the nonmagnetic layer 2. In the case of the magnetic domain wall motion element 100 shown in FIG. 3, the magnetization M A1、 M A3a、 M A3b、 M A2 and the magnetization M of the reference layer 3 3The resistance value of the domain wall motion element 100 changes depending on the relative angle with respect to the magnetic domain A3. When the ratio of the first magnetic domain A3a increases, the resistance value of the domain wall motion element 100 decreases, and when the ratio of the second magnetic domain A3b increases, the resistance value of the domain wall motion element 100 increases. By precisely controlling the position of the domain wall DW, the resistance value can be precisely controlled, enabling analog-like multi-value data recording.

[0047] In the domain wall motion element 100, the reference layer 3 overlaps with the first region A1 and the second region A2 with the nonmagnetic layer 2 sandwiched therebetween. The first region A1 and the second region A2, whose magnetizations are fixed, do not contribute to a change in the resistance value of the domain wall motion element 100. In other words, when the ratio of the first region A1 and the second region A2 in the domain wall motion layer 1 increases, the MR ratio, which is the ratio of the maximum resistance value to the minimum resistance value, of the domain wall motion element 100 decreases.

[0048] The domain wall displacement layer 1 includes a magnetic material. The domain wall displacement layer 1 may be a ferromagnetic material, a ferrimagnetic material, or a combination of these with an antiferromagnetic material whose magnetic state can be changed by a current. The domain wall displacement layer 1 preferably contains at least one element selected from the group consisting of Co, Ni, Fe, Pt, Pd, Gd, Tb, Mn, Ge, and Ga. Examples of materials used for the domain wall displacement layer 1 include a laminated film of Co and Ni, a laminated film of Co and Pt, a laminated film of Co and Pd, a laminated film of CoFe and Pd, a 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. In addition, the laminated film of Co and Ni, the laminated film of Co and Pt, and the laminated film of Co and Pd have large coercive force, and the moving speed of the domain wall DW is slow. The antiferromagnetic material is, for example, Mn 3 X (X is Sn, Ge, Ga, Pt, Ir, etc.), CuMnAs, Mn 2 The domain wall displacement layer 1 may be made of a material similar to that of the reference layer 3 described later.

[0049] The nonmagnetic layer 2 is located between the domain wall displacement layer 1 and the reference layer 3. The nonmagnetic layer 2 is laminated on one surface of the reference layer 3, for example.

[0050] The non-magnetic layer 2 is made of, for example, a non-magnetic insulator, a semiconductor, or a metal. The non-magnetic insulator is, for example, Al. 2 O 3 , SiO 2 , MgO, MgAl 2 O 4 , and materials in which part of these Al, Si, and Mg are replaced with Zn, Be, or the like. These materials have a large band gap and excellent insulating properties. When the nonmagnetic layer 2 is made of a nonmagnetic insulator, the nonmagnetic layer 2 is a tunnel barrier layer. Examples of nonmagnetic metals include Cu, Au, Ag, and the like. Examples of nonmagnetic semiconductors include Si, Ge, CuInSe 2 , CuGaSe 2 , Cu(In,Ga)Se 2 etc.

[0051] The thickness of the non-magnetic layer 2 is, for example, 20 Å or more, and may be 25 Å or more. If the thickness of the non-magnetic layer 2 is large, the resistance area area (RA) of the domain wall motion element 100 becomes large. The resistance area area (RA) of the domain wall motion element 100 is 1×10 4 Ωμm 2 It is preferable that the value is 5×10 or more. 4 Ωμm 2 The resistance area product (RA) of the domain wall motion element 100 is expressed as the product of the element resistance of one domain wall motion element 100 and the element cross-sectional area of ​​the domain wall motion element 100 (the area of ​​a cross section obtained by cutting the nonmagnetic layer 2 in the xy plane).

[0052] The reference layer 3 sandwiches the nonmagnetic layer 2 together with the domain wall displacement layer 1. The reference layer 3 is, for example, stacked on the third electrode 40. The reference layer 3 is located so as to overlap with the domain wall displacement layer 1 in the z direction. The reference layer 3 is located so as to overlap at least partially with each of the first region A1, the second region A2, and the third region A3 in the z direction. The magnetization M of the reference layer 3 3 is the magnetization M of the third region A3 of the domain wall displacement layer 1. A3a , M A3b The magnetization M of the reference layer 3 is more difficult to reverse. 3 is the magnetization M of the third region A3 A3a , M A3bWhen an external force strong enough to reverse the magnetization is applied, the magnetization direction is fixed and does not change. The reference layer 3 is sometimes called a magnetization fixed layer. The reference layer 3 may be made of multiple layers. For example, it may have multiple ferromagnetic layers and an intermediate layer sandwiched between the multiple ferromagnetic layers. The two ferromagnetic layers sandwiching the intermediate layer may be magnetically coupled to form a synthetic antiferromagnetic structure (SAF).

[0053] The reference layer 3 includes a ferromagnetic material. The reference layer 3 includes, for example, a material that is likely to provide a coherent tunnel effect between the reference layer 3 and the domain wall displacement layer 1. The reference layer 3 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, an alloy containing these metals and at least one of B, C, and N, or the like. The reference layer 3 is, for example, Co-Fe, Co-Fe-B, or Ni-Fe.

[0054] The reference layer 3 may be, for example, a Heusler alloy. Heusler alloys are half-metallic and have high spin polarizability. Heusler alloys are either XYZ or X 2 It is an intermetallic compound with the chemical composition YZ, where X is a transition metal element or a precious metal element of the Co, Fe, Ni, or Cu group on the periodic table, Y is a transition metal element or an element type of X of the Mn, V, Cr, or Ti group, and Z is a typical element of groups III to V. For example, Co 2 FeSi, Co 2 FeGe, Co 2 FeGa, Co. 2 MnSi, Co 2 Mn 1-a Fe a Al b S 1-b , Co 2 FeGe 1-c Ga c etc.

[0055] The first magnetization pinned layer 20 and the second magnetization pinned layer 30 are directly or indirectly connected to the domain wall movement layer 1. Indirectly connected means that another layer is sandwiched between the first magnetization pinned layer 20 and the domain wall movement layer 1, and between the second magnetization pinned layer 30 and the domain wall movement layer 1. The first magnetization pinned layer 20 and the second magnetization pinned layer 30 are, for example, on the domain wall movement layer 1. The first magnetization pinned layer 20 and the second magnetization pinned layer 30 are spaced apart in the x direction. The first magnetization pinned layer 20 is connected to the magnetization M of the first region A1. A1 The second magnetization fixed layer 30 fixes the magnetization M of the second region A2. A2 The first magnetization pinned layer 20 and the second magnetization pinned layer 30 are located, for example, at positions overlapping the nonmagnetic layer 2 and the reference layer 3 in the z direction.

[0056] The first magnetization pinned layer 20 and the second magnetization pinned layer 30 include, for example, a ferromagnetic layer. The first magnetization pinned layer 20 and the second magnetization pinned layer 30 include, for example, a material different from that of the domain wall displacement layer 1 and have a different film configuration. The first magnetization pinned layer 20 and the second magnetization pinned layer 30 may be composed of, for example, a plurality of layers. For example, they may have a plurality of ferromagnetic layers and an intermediate layer sandwiched between the plurality of ferromagnetic layers. The two ferromagnetic layers sandwiching the intermediate layer may be magnetically coupled to form a synthetic antiferromagnetic structure (SAF). The first magnetization pinned layer 20 and the second magnetization pinned layer 30 may have different film configurations.

[0057] The third electrode 40 is electrically connected to the reference layer 3. The third electrode 40 is, for example, located closer to the substrate Sub than the reference layer 3. The first electrode 41 is, for example, electrically connected to the first region A1 via the first magnetization fixed layer 20. The second electrode 42 is, for example, electrically connected to the second region A2 via the second magnetization fixed layer 30. The third electrode 40, the first electrode 41, and the second electrode 42 include, for example, a nonmagnetic conductive material and include a material having a higher thermal conductivity than the domain wall displacement layer 1 and the reference layer 3. The third electrode 40, the first electrode 41, and the second electrode 42 may be formed of, for example, different materials from each other. The third electrode 40, the first electrode 41, and the second electrode 42 are, for example, via wiring extending in the z direction.

[0058] The domain wall motion element 100 according to the first embodiment has a large MR ratio, and can increase the number of bits for multi-value data recording.

[0059] As described above, the domain wall motion element 100 is located at a position where the first region A1 and the second region A2 overlap the reference layer 3 in the z direction with the nonmagnetic layer 2 sandwiched therebetween in order to enhance integration. The first region A1 and the second region A2 are shorter in the y direction than the third region A3. By adopting such a structure, the ratio of the first region A1 and the second region A2 that do not contribute to the change in resistance value in the domain wall motion layer 1 can be reduced. In other words, the MR ratio, which is the ratio of the maximum resistance value to the minimum resistance value of the domain wall motion element 100, can be increased, and the number of bits of multi-value data recording can be increased. Note that the idea of ​​forming the width of the magnetization fixed region narrower than the width of the domain wall motion region in order to increase the number of bits of multi-value data recording, as in the domain wall motion element according to this embodiment, runs counter to the conventional technical common sense of forming the width of the magnetization fixed region wider than the width of the domain wall motion region in order to stabilize the magnetization fixing function.

[0060] In addition, the first region A1 and the second region A2 of the domain wall motion element 100 according to the first embodiment have a length in the x direction longer than that in the y direction. If the length in the y direction of the first region A1 and the second region A2 is made shorter than that of the third region A3, the current density during data writing will be higher in the first region A1 and the second region A2 than in the third region A3. The domain wall DW moves at a high speed when the current density increases. By making the length in the x direction of the first region A1 and the second region A2 longer than that in the y direction, the ratio of the first region A1 and the second region A2 in the domain wall motion layer 1 is reduced, and it is possible to prevent the domain wall DW from reaching the outer end of the first region A1 and the second region A2 and the entire domain wall motion layer 1 from becoming a single magnetic domain.

[0061] In the domain wall motion element 100 according to the first embodiment, the boundary between the first region A1 and the third region A3 and the boundary between the second region A2 and the third region A3 are each approximately perpendicular to the x-direction, which is the extension direction of the domain wall motion layer 1. The boundary between the first region A1 and the third region A3 and the boundary between the second region A2 and the third region A3 are perpendicular to each other, so that the domain wall DW can be moved in a state nearly parallel to the y-direction at all times. If the domain wall DW always moves in a state nearly parallel to the y-direction, the amount of change in the resistance value can be kept constant even when the position of the domain wall DW is precisely controlled to change the resistance value in an analog manner.

[0062] 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, for example, by using MOKE (Magneto Optical Kerr Effect). Measurement by MOKE is a measurement method that uses the magneto-optical effect (magnetic Kerr effect) in which linearly polarized light is incident on the measurement object and the polarization direction rotates.

[0063] The domain wall motion element 100 can be fabricated by a known method. Each layer of the domain wall motion element 100 is formed and processed into a predetermined shape. The layers can be formed by sputtering, chemical vapor deposition (CVD), electron beam deposition (EB deposition), atomic laser deposition, or the like. Each layer can be processed by using techniques such as photolithography and etching (e.g., Ar etching).

[0064] "Second embodiment" Fig. 5 is a plan view of the domain wall motion element 101 according to the second embodiment as viewed from the z direction. In Fig. 5, the first electrode 41, the second electrode 42, and the portion of the third electrode 40 that overlaps with the magnetoresistance effect portion 10 are indicated by dashed lines. The domain wall motion element 101 according to the second embodiment differs from the first embodiment in the configuration of the first region A1. In the second embodiment, the same configurations as in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0065] As shown in FIG. 5, the first region A1A is composed of a first portion A1Aa and a second portion A1Ab. The length WA1Aa is the length W of the third region A3 in the y direction A3 The length W of the second portion A1Ab in the y direction is longer than A1Ab is the length W of the third region A3 in the y direction A3 The first portion A1Aa is located closer to the third region A3 than the second portion A1Ab in the x direction.

[0066] The domain wall motion element 101 according to the second embodiment has the same effects as the domain wall motion element 100 according to the first embodiment. In addition, in the first region A1A, the first portion A1Aa having a length in the y direction longer than the third region A3 is provided on the third region A3 side to reduce the current density during data writing, thereby preventing the domain wall DW from penetrating into the first region A1A.

[0067] "Third embodiment" Fig. 6 is a plan view of the domain wall motion element 102 according to the third embodiment as viewed from the z direction. In Fig. 6, the first electrode 41, the second electrode 42, and the portion of the third electrode 40 that overlaps with the magnetoresistance effect portion 10 are indicated by dashed lines. The domain wall motion element 102 according to the third embodiment differs from the first embodiment in the configurations of the first region A1 and the third region A3. In the second embodiment, the same components as in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0068] As shown in FIG. 6, the length of the first region A1B in the y direction gradually decreases from the end in contact with the third region A3A toward the opposite end in the x direction. For example, the length of the first region A1B in the y direction changes continuously from the end in contact with the third region A3A toward the opposite end in the x direction. Also, the third region A3A has a y direction length W A3AC The length W of the end in the y direction in the x direction is A3AE 3. The third region A3A has a thickness t C than the thickness t E is thicker, and the thickness increases continuously from the center in the x direction to the end in the x direction.

[0069] The domain wall motion element 102 according to the third embodiment has the same effects as the domain wall motion element 100 according to the first embodiment. By gradually shortening the y-direction length of the first region A1B from the end in contact with the third region A3A toward the opposite end in the x-direction, it is possible to suppress a sudden increase in current density in the first region A1B during data writing, and to prevent the domain wall DW from reaching the outer end of the element and the entire domain wall motion layer 1 from becoming a single magnetic domain. Furthermore, by continuously increasing the film thickness of the third region A3 from the center in the x-direction toward the end, it is possible to suppress heat generation due to current concentration at the corners. Furthermore, the y-direction length W of the center in the x-direction of the third region A3 is A3AC The length W of the end in the y direction in the x direction A3AE By shortening the length of the third region A3, it is possible to suppress a decrease in the current density at the end of the third region A3 during data writing caused by an increase in the film thickness. If the current density at the end of the third region A3 during data writing is lower than that in the central portion, there is a risk that the domain wall DW will be trapped at the end.

[0070] "Fourth embodiment" FIG. 7 is a cross-sectional view of the domain wall motion element 103 according to the fourth embodiment cut in the xz plane passing through the center of the domain wall motion layer 1 in the y direction. FIG. 7 is a cross-section taken along the line A'-A' in FIG. 8. FIG. 8 is a plan view of the domain wall motion element 103 as viewed from the z direction. FIG. 8 shows the first electrode 41, the second electrode 42, and the portion of the third electrode 40A that overlaps with the magnetoresistance effect part 10 with dashed lines. The arrows shown in the figure are an example of the orientation direction of magnetization of a ferromagnetic body. The domain wall motion element 103 according to the fourth embodiment differs from the first embodiment in the configuration of the third electrode 40. In the fourth embodiment, the same reference numerals are used for the same configuration as in the first embodiment, and description thereof will be omitted.

[0071] As shown in Figures 7 and 8, the first surface 40a of the third electrode 40A, which is the surface closest to the reference layer 3, overlaps with the entire third region A3 when viewed in a plane from the z direction, and its peripheral portion overlaps with the first region A1 and the second region A2.

[0072] The domain wall motion device 103 according to the fourth embodiment has the same effects as the domain wall motion device 100 according to the first embodiment. In addition, by arranging the first surface 40a of the third electrode 40A so as to overlap the entire third region A3 in a plan view from the z direction, the flatness of the third region A3 is improved and the domain wall DW moves smoothly.

[0073] The dimensions of the via diameter are often fixed by the manufacturing process. In other words, there are restrictions on the selection of the via diameter, and it may not be possible to make it large. The third region A3 is preferably as long as possible in order to increase the number of bits for multi-value data recording. By arranging the outer periphery of the first surface 40a of the third electrode 40A so that it overlaps with the first region A1 and the second region A2 in a plan view from the z direction, it is possible to obtain the effect of increasing the flatness of the third region A3 described above, while making the third region A3 as long as possible within the restrictions of the via diameter.

[0074] "Fifth embodiment" Fig. 9 is a plan view of the domain wall motion element 104 according to the fifth embodiment as viewed from the z direction. In Fig. 9, the first electrode 41 and the second electrode 42 are indicated by dashed lines. The domain wall motion element 104 according to the fifth embodiment differs from the first embodiment in the configuration of the third electrode 40. In the fifth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0075] As shown in FIG. 9, the first surface 40b of the third electrode 40B, which is the surface closest to the reference layer 3, overlaps with the entire domain wall displacement layer 1 in plan view from the z direction.

[0076] The domain wall motion element 104 according to the fifth embodiment has the same effects as the domain wall motion element 100 according to the first embodiment. In addition, by arranging the first surface 40b of the third electrode 40B containing a conductive material so as to overlap the entire domain wall motion layer 1 in a plan view from the z direction, the heat dissipation of the entire domain wall motion layer 1 including the first region A1 and the second region A2 is improved. When the heat dissipation of the entire domain wall motion layer 1 is improved, the magnetization fixing function of the first region A1 and the second region A2 is stabilized, and the reliability of data recording is improved.

[0077] Sixth embodiment Fig. 10 is a plan view of the domain wall motion element 105 according to the sixth embodiment as viewed from the z direction. In Fig. 10, the first electrode 41 and the second electrode 42 are indicated by dashed lines. The domain wall motion element 105 according to the sixth embodiment differs from the first embodiment in the configuration of the third electrode 40. In the sixth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0078] As shown in FIG. 10, the first surface 40c of the third electrode 40C, which is the surface closest to the reference layer 3, overlaps with the entire domain wall displacement layer 1 in a plan view from the z direction, and has a maximum length L Y is the maximum length in the x direction, L X is shorter than.

[0079] The domain wall motion element 105 according to the sixth embodiment has the same effect as the domain wall motion element 100 according to the first embodiment. In order to increase the number of bits for multi-value data recording, it is preferable that the domain wall motion element has a shape that is long in one direction. The first surface 40c of the third electrode 40C is arranged so as to overlap the entire domain wall motion layer 1 in a plan view from the z direction, and the maximum length L in the y direction is Y is the maximum length L in the x direction in which the domain wall displacement layer 1 extends. X By making the shape shorter than the above, the heat dissipation of the entire domain wall motion layer 1 is improved, and the first surface 40c is shaped to fit the domain wall motion layer 1, improving the integration of the domain wall motion elements.

[0080] Seventh embodiment FIG. 11 is a cross-sectional view of the domain wall motion element 106 according to the seventh embodiment cut in the xz plane passing through the center of the domain wall motion layer 1 in the y direction. FIG. 11 is a cross-section taken along the line A''-A'' in FIG. 12. FIG. 12 is a plan view of the domain wall motion element 106 as viewed from the z direction. In FIG. 12, the first electrode 41, the second electrode 42, and the portion of the third electrode 40D that overlaps with the magnetoresistance effect unit 10 are indicated by dashed lines. The arrows shown in the figure are an example of the orientation direction of magnetization of a ferromagnetic body. The domain wall motion element 106 according to the seventh embodiment differs from the first embodiment in the configuration of the first magnetization pinned layer 20 and the third electrode 40. In the seventh embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted.

[0081] As shown in FIG. 11, the thickness t 20A is the thickness t of the second magnetization pinned layer 30 30 The thickness t of the first magnetization fixed layer 20A is thicker than 20A and the thickness t of the second magnetization pinned layer 30 30 When the magnetic fields are different, it becomes easier to pin the magnetizations in different directions by utilizing the difference in coercivity.

[0082] The domain wall motion device 106 according to the seventh embodiment has the same effect as the domain wall motion device 100 according to the first embodiment. As shown in Fig. 12, in plan view from the z direction, the centers of gravity of the third electrode 40D and the domain wall motion layer 1 are offset. As shown in Fig. 12, in plan view from the z direction, the distance L between the geometric center O of the first surface 40d, which is the surface of the third electrode 40D closest to the reference layer 3, and the first magnetization fixed layer 20A is 1 / 2. 1 is the distance L between the geometric center O of the first surface 40d and the third magnetization fixed layer 30. 2 The first magnetization pinned layer 20A, which is thicker than the second magnetization pinned layer 30, has a higher resistance value than the second magnetization pinned layer 30 and is more likely to generate heat during data writing. By moving the first surface 40d of the third electrode 40D, which includes a conductive material, toward the first magnetization pinned layer 20A, the heat distribution occurring between the first region A1 side and the second region A2 side of the domain wall displacement layer 1 can be suppressed, and the reliability of data recording is improved. In FIG. 11 and FIG. 12, an example in which the first surface 40d overlaps the first region A1 in a plan view from the z direction is shown, but the first surface 40d may overlap the first region A1 and the second region A2, or the first surface 40d may not overlap either the first region A1 or the second region A2.

[0083] Eighth embodiment Fig. 13 is a plan view of the vicinity of the first region A1C of the domain wall motion element 107 according to the eighth embodiment as viewed from the z direction. In Fig. 13, the first electrode 41 is indicated by a dashed line. The domain wall motion element 107 according to the eighth embodiment differs from the first embodiment in the configuration of the first region A1. In the eighth embodiment, the same reference numerals are used for the same configuration as in the first embodiment, and the description thereof will be omitted.

[0084] 13, the first electrode 41 overlaps with the entire first region A1C in plan view from the z direction. In plan view from the z direction, the distance between the outer periphery of the first electrode 41 and the outer periphery of the first region A1C is shortest (L min The first region A1C has a curved outer periphery other than the side in contact with the third region A3 when viewed in a plan view from the z direction, for example.

[0085] The domain wall motion element 107 according to the eighth embodiment has the same effect as the domain wall motion element 100 according to the first embodiment. The first region A1C is overlapped with the first electrode 41, thereby improving heat dissipation. However, the outer periphery of the first electrode 41 is in contact with the insulating layer 90, and therefore has poorer heat dissipation than the center of the first electrode 41. By minimizing the portion of the first region A1C where the distance to the outer periphery of the first electrode 41 is short, the magnetization fluctuation of the first region A1C due to heat generation can be suppressed, and the reliability of data recording is improved. In FIG. 13, an example is shown in which the distance between the outer periphery of the first electrode 41 and the outer periphery of the first region A1C is shortest at the end of the first region A1C that is in contact with the third region A3 and the end opposite in the x direction, but the portion where the distance between the outer periphery of the first electrode 41 and the outer periphery of the first region A1C is shortest may be any other portion.

[0086] Although several embodiments have been presented so far as examples of domain wall motion elements, the present invention is not limited to these embodiments, and various modifications are possible without departing from the spirit and scope of the invention.

[0087] For example, although the above description shows an example in which the reference layer 3 is closer to the substrate Sub than the domain wall motion layer 1, the reference layer 3 may be located farther from the substrate Sub than the domain wall motion layer 1, as in Modification 1 shown in Fig. 14. Fig. 14 is a cross-sectional view taken along the xz plane passing through the center in the y direction of the domain wall motion element 108 according to Modification 1. The structure in Fig. 14 in which the reference layer 3 is located farther from the substrate than the domain wall motion layer 1 is called a top pin structure.

[0088] In addition, the characteristic configurations of the above-described embodiments and modifications may be combined. [Explanation of symbols]

[0089] 1...Domain wall displacement layer 2...Nonmagnetic layer 3…Reference layer 10...Magnetoresistance effect section 20,20A...first magnetization fixed layer 30…Second magnetization fixed layer 40,40A,40B,40C,40D…3rd electrode 40a, 40b, 40c, 40d…first side 41...1st electrode 42…Second electrode 90...Insulating layer 100, 101, 102, 103, 104, 105, 106, 107, 108... Domain wall motion element 200…Magnetic array A1,A1A,A1B,A1C…First area A1Aa…Part 1 A1Ab…Second part A2…Second area A3,A3A…Third area CL: Second wiring DW…Domain wall RL…Third wiring Sub…Substrate SW1: First switching element SW2: Second switching element SW3: Third switching element w1,w2…Wiring WL…1st wiring

Claims

1. a magnetoresistive effect section in which a reference layer and a domain wall displacement layer, each of which includes a ferromagnetic material, and a nonmagnetic layer located between the reference layer and the domain wall displacement layer are stacked in a first direction; the domain wall displacement layer extends in a second direction perpendicular to the first direction and includes a first region having a fixed magnetization direction, a second region having a fixed magnetization direction in a direction different from the magnetization direction of the first region, and a third region located between the first region and the second region in the second direction and having a variable magnetization direction; A first electrode electrically connected to the first region; A second electrode electrically connected to the second region; a third electrode located on an opposite side of the nonmagnetic layer with respect to the reference layer in the first direction and electrically connected to the reference layer; a first magnetization fixed layer located between the first region and the first electrode and configured to fix the magnetization of the first region; a second magnetization fixed layer located between the second region and the second electrode and fixing the magnetization of the second region; the reference layer overlaps with at least a portion of the first region and the second region in a plan view from the first direction, At least one of the first region and the second region has a first portion having a length in a third direction perpendicular to the first direction and the second direction longer than the third region, and a second portion having a length in the third direction shorter than the third region, The first portion is located closer to the third region than the second portion in the second direction.

2. a magnetoresistive effect section in which a reference layer and a domain wall displacement layer, each of which includes a ferromagnetic material, and a nonmagnetic layer located between the reference layer and the domain wall displacement layer are stacked in a first direction; the domain wall displacement layer extends in a second direction perpendicular to the first direction and includes a first region having a fixed magnetization direction, a second region having a fixed magnetization direction in a direction different from the magnetization direction of the first region, and a third region located between the first region and the second region in the second direction and having a variable magnetization direction; A first electrode electrically connected to the first region; A second electrode electrically connected to the second region; a third electrode located on an opposite side of the nonmagnetic layer with respect to the reference layer in the first direction and electrically connected to the reference layer; a first magnetization fixed layer located between the first region and the first electrode and configured to fix the magnetization of the first region; a second magnetization fixed layer located between the second region and the second electrode and fixing the magnetization of the second region; the reference layer overlaps with at least a portion of the first region and the second region in a plan view from the first direction, At least one of the first region and the second region has a portion that is shorter in length in a third direction perpendicular to the first direction and the second direction than the third region, A domain wall motion element, wherein the third region has a thickness at its ends in the second direction that is thicker than a thickness at its central portion in the second direction, and the length of the ends in the third direction is shorter than the length of the central portion in the third direction.

3. a magnetoresistive effect section in which a reference layer and a domain wall displacement layer, each of which includes a ferromagnetic material, and a nonmagnetic layer located between the reference layer and the domain wall displacement layer are stacked in a first direction; the domain wall displacement layer extends in a second direction perpendicular to the first direction and includes a first region having a fixed magnetization direction, a second region having a fixed magnetization direction in a direction different from the magnetization direction of the first region, and a third region located between the first region and the second region in the second direction and having a variable magnetization direction; A first electrode electrically connected to the first region; A second electrode electrically connected to the second region; a third electrode located on an opposite side of the nonmagnetic layer with respect to the reference layer in the first direction and electrically connected to the reference layer; a first magnetization fixed layer located between the first region and the first electrode and configured to fix the magnetization of the first region; a second magnetization fixed layer located between the second region and the second electrode and fixing the magnetization of the second region; the reference layer overlaps with at least a portion of the first region and the second region in a plan view from the first direction, At least one of the first region and the second region has a portion that is shorter in length in a third direction perpendicular to the first direction and the second direction than the third region, a first surface of the third electrode that is closest to the reference layer in a plan view from the first direction, the outer periphery of the first surface overlaps with at least one of the first region and the second region.

4. a magnetoresistive effect section in which a reference layer and a domain wall displacement layer, each of which includes a ferromagnetic material, and a nonmagnetic layer located between the reference layer and the domain wall displacement layer are stacked in a first direction; the domain wall displacement layer extends in a second direction perpendicular to the first direction and includes a first region having a fixed magnetization direction, a second region having a fixed magnetization direction in a direction different from the magnetization direction of the first region, and a third region located between the first region and the second region in the second direction and having a variable magnetization direction; A first electrode electrically connected to the first region; A second electrode electrically connected to the second region; a third electrode located on an opposite side of the nonmagnetic layer with respect to the reference layer in the first direction and electrically connected to the reference layer; a first magnetization fixed layer located between the first region and the first electrode and configured to fix the magnetization of the first region; a second magnetization fixed layer located between the second region and the second electrode and fixing the magnetization of the second region; the reference layer overlaps with at least a portion of the first region and the second region in a plan view from the first direction, At least one of the first region and the second region has a portion that is shorter in length in a third direction perpendicular to the first direction and the second direction than the third region, a first surface of the third electrode, which is a surface of the third electrode closest to the reference layer, overlaps with the entire domain wall motion layer in a plan view from the first direction.

5. a magnetoresistive effect section in which a reference layer and a domain wall displacement layer, each of which includes a ferromagnetic material, and a nonmagnetic layer located between the reference layer and the domain wall displacement layer are stacked in a first direction; the domain wall displacement layer extends in a second direction perpendicular to the first direction and includes a first region having a fixed magnetization direction, a second region having a fixed magnetization direction in a direction different from the magnetization direction of the first region, and a third region located between the first region and the second region in the second direction and having a variable magnetization direction; A first electrode electrically connected to the first region; A second electrode electrically connected to the second region; a third electrode located on an opposite side of the nonmagnetic layer with respect to the reference layer in the first direction and electrically connected to the reference layer; a first magnetization fixed layer located between the first region and the first electrode and configured to fix the magnetization of the first region; a second magnetization fixed layer located between the second region and the second electrode and fixing the magnetization of the second region; the reference layer overlaps with at least a portion of the first region and the second region in a plan view from the first direction, At least one of the first region and the second region has a portion that is shorter in length in a third direction perpendicular to the first direction and the second direction than the third region, A domain wall motion element, wherein the film thickness of the first magnetization fixed layer is thicker than the film thickness of the second magnetization fixed layer, and when viewed in a planar view from the first direction, the distance from the geometric center of a first surface, which is the surface of the third electrode closest to the reference layer, to the first magnetization fixed layer is shorter than the distance from the geometric center of the first surface to the second magnetization fixed layer.

6. 6. The domain wall motion element according to claim 1, further comprising a substrate on an opposite side to the reference layer with respect to the third electrode in the first direction.

7. 7. The domain wall motion element according to claim 1, wherein at least one of the first region and the second region has a length in the second direction longer than a length in the third direction.

8. A domain wall motion element according to any one of claims 1 to 7, wherein the length in the third direction of at least one of the first region and the second region gradually shortens from an end portion adjacent to the third region toward an opposite end portion in the second direction.

9. The domain wall motion element according to any one of claims 1 to 8, wherein a first surface, which is the surface of the third electrode closest to the reference layer, has a length of the longest part in the third direction that is shorter than a length of the longest part in the second direction.

10. The domain wall motion element according to any one of claims 1 to 9, wherein, in a planar view from the first direction, the entire first region overlaps with the first electrode, and the distance from the first region to the outer periphery of the first electrode is shortest at a certain point.

11. A magnetic recording array comprising a plurality of domain wall motion elements according to any one of claims 1 to 10.

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