Domain wall motion element and magnetic array

Abstract

To provide a domain wall motion element that can stabilize the operation of a domain wall.SOLUTION: The domain wall motion element includes a laminated body located above a substrate and having a ferromagnetic layer, a nonmagnetic layer, and a domain wall motion layer stacked in order from the side closer to the substrate, a first conductive layer, and a first surface layer. The nonmagnetic layer is sandwiched between the ferromagnetic layer and the domain wall motion layer. The first conductive layer is connected to the top surface of the domain wall motion layer. The first surface layer is in contact with at least a portion of the top surface of the domain wall motion layer. The resistivity of the first surface layer is higher than the resistivity of the domain wall motion layer.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] As the limits of miniaturization become apparent, attention is being focused on next-generation non-volatile memory as a replacement for flash memory, etc. Examples of next-generation non-volatile memory include MRAM (Magnetoresistive Random Access Memory), ReRAM (Resistance Random Access Memory), and PCRAM (Phase Change Random Access Memory).

[0003] MRAM uses the resistance change caused by the change in the direction of magnetization to record data. To achieve a larger capacity recording memory, efforts are being made to miniaturize the elements that make up the memory and to increase the number of recording bits per element.

[0004] Patent Document 1 describes a domain wall motion element that can record multi-valued or digital data by moving a domain wall in a domain wall motion layer (first ferromagnetic layer). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5445970 Summary of the Invention [Problem to be solved by the invention]

[0006] The magnetic resistance of a domain wall motion element varies depending on the position of the domain wall. If there are impurities or defects in the domain wall motion layer, the domain wall is likely to be trapped by the impurities or defects. In other words, if there are unintended impurities or defects in the domain wall motion layer, the motion of the domain wall in the domain wall motion element becomes unstable. The domain wall motion element of Patent Document 1 also sometimes contains impurities or defects in the domain wall motion layer, causing the motion of the domain wall to become unstable.

[0007] The present invention has been made in view of the above problems, and has as its object to provide a domain wall motion element and a magnetic array that can stabilize the motion of the domain wall. [Means for solving the problem]

[0008] (1) A domain wall motion element according to a first aspect of the present invention comprises a laminate located above a substrate and having a ferromagnetic layer, a non-magnetic layer, and a domain wall motion layer stacked in order from the side closest to the substrate, a first conductive layer, and a first surface layer, wherein the non-magnetic layer is sandwiched between the ferromagnetic layer and the domain wall motion layer, the first conductive layer is connected to the upper surface of the domain wall motion layer, the first surface layer is in contact with at least a portion of the upper surface of the domain wall motion layer, and the resistivity of the first surface layer is higher than the resistivity of the domain wall motion layer.

[0009] (2) The domain wall motion element according to the above aspect may further include an insulating layer in contact with the top surface of the first surface layer.

[0010] (3) In the domain wall motion element according to the above aspect, the first surface layer may contain amorphous or microcrystalline material.

[0011] (4) In the domain wall motion element according to the above aspect, the first surface layer may contain at least one element selected from the group consisting of Bi, Ni, Cr, Ti, Zr, and W.

[0012] (5) In the domain wall motion element according to the above aspect, the first surface layer may have a thickness of 2 nm or less.

[0013] (6) In the domain wall motion element according to the above aspect, the direction of easy magnetization of the domain wall motion layer may intersect with a plane in which the domain wall motion layer extends.

[0014] (7) In the domain wall motion element according to the above aspect, at least a portion of the first conductive layer may be sandwiched between the first surface layer and the domain wall motion layer.

[0015] (8) The domain wall motion element according to the above aspect may further include a second surface layer in contact with an upper surface of the first conductive layer, and the resistivity of the second surface layer may be higher than the resistivity of the domain wall motion layer.

[0016] (9) The domain wall motion element according to the above aspect may further include a third surface layer in contact with a side surface of the first conductive layer, and the resistivity of the third surface layer may be higher than the resistivity of the domain wall motion layer.

[0017] (10) A magnetic array according to a second aspect of the present invention includes a substrate and a plurality of domain wall motion elements according to the above aspect, and the plurality of domain wall motion elements may be integrated on the substrate. [Effects of the Invention]

[0018] The domain wall motion element and magnetic array according to the above aspects can stabilize the motion of the domain wall in the domain wall motion element. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a configuration diagram of a magnetic recording array according to a first embodiment. [Figure 2] 1 is a cross-sectional view of a main part of a magnetic recording array according to a first embodiment. [Figure 3] 1 is a cross-sectional view of a domain wall motion element according to a first embodiment. [Figure 4] This is the result of electron diffraction of the microcrystals using a transmission electron microscope (TEM). [Figure 5] This is the result of electron diffraction of the amorphous material using a transmission electron microscope (TEM). [Figure 6] FIG. 10 is a cross-sectional view of a domain wall motion element according to a comparative example. [Figure 7] FIG. 10 is a cross-sectional view of a domain wall motion element according to a first modified example. [Figure 8] FIG. 10 is a cross-sectional view of a domain wall motion element according to a second modification. [Figure 9] FIG. 11 is a cross-sectional view of a domain wall motion element according to a third modification. [Figure 10] FIG. 10 is a cross-sectional view of a domain wall motion element according to a fourth modification. [Figure 11] FIG. 13 is a cross-sectional view of a domain wall motion element according to a fifth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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 portions enlarged for the sake of clarity, and the dimensional ratios of each component may differ from the actual ratios. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate modifications can be made within the scope of the present invention. Furthermore, although the compositional formulas described in the specification are stoichiometric, deviations from the stoichiometric composition are permitted within the scope of maintaining the structure.

[0021] First, the directions will be defined. The +x direction, the -x direction, the +y direction, and the -y direction are directions substantially parallel to one surface of the substrate Sub (see FIG. 2), which will be described later. The +x direction is the direction in which the domain wall motion layer 30, which will be described later, extends, and is the direction from the first conductive layer 60 to the second conductive layer 70, which will be described later. The -x direction is the direction opposite to the +x direction. When the +x direction and the -x direction are not distinguished, they will simply be referred to as the "x direction." The +y direction is a direction perpendicular to the x direction. The -y direction is the direction opposite to the +y direction. When the +y direction and the -y direction are not distinguished, they will simply be referred to as the "y direction." The +z direction is the direction from the substrate Sub, which will be described later, to the domain wall motion element 100. The -z direction is the direction opposite to the +z direction. When the +z direction and the -z direction are not distinguished, they will simply be referred to as the "z direction." In this specification, "extending in the x-direction" means that the dimension in the x-direction is greater than the smallest dimension among the dimensions in the x-direction, y-direction, and z-direction. The same applies to extending in other directions.

[0022] Next, the terms used in this embodiment will be defined. In this specification, "connection" refers to a state in which a subject can have an electrical effect on an object (a connection target), and is not limited to a state in which a subject is in direct contact with an object. In this specification, "contact" refers to a state in which a subject is in direct contact with an object. In addition, "above" refers to a state in which a subject is above an object, and includes both a state in which a subject is above an object and in contact with the object, and a state in which a subject is above an object and is spaced apart from the object.

[0023] [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 Wp, a plurality of second wirings Cm, a plurality of third wirings Rp, 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 product-sum calculator, a neuromorphic device, a spin memristor, or a magneto-optical element.

[0024] <1st wiring, 2nd wiring, 3rd wiring> Each of the first wirings Wp is a write wiring. Each of the first wirings Wp electrically connects a power source to one or more domain wall motion elements 100. The power source is connected to one end of the magnetic array 200 during use.

[0025] Each of the second wirings Cm 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 Cm electrically connects a reference potential to one or more domain wall motion elements 100. The reference potential is, for example, ground. The second wirings Cm 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.

[0026] Each of the third wirings Rp is a read wiring. Each of the third wirings Rp electrically connects a power source to one or more domain wall motion elements 100. The power source is connected to one end of the magnetic array 200 during use.

[0027] <First switching element, second switching element, third switching element> 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 Wp. The second switching element SW2 is connected between the domain wall motion element 100 and a second wiring Cm. The third switching element SW3 is connected between the domain wall motion element 100 and a third wiring Rp.

[0028] When the first switching element SW1 and the second switching element SW2 are turned on, a write current flows between the first wiring Wp and the second wiring Cm connected to the 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 Cm and the third wiring Rp connected to the predetermined domain wall motion element 100.

[0029] 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, elements that utilize a phase change of a crystal layer such as a transistor or an Ovonic Threshold Switch (OTS), elements that utilize a change in band structure such as a Metal-Insulator Transition (MIT) switch, elements that utilize a breakdown voltage such as a Zener diode or an avalanche diode, or elements that change conductivity according to a change in atomic position.

[0030] Any of the first switching element SW1, the second switching element SW2, and the third switching element SW3 may be shared by 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 Wp. For example, when the second switching element SW2 is shared, one second switching element SW2 is provided upstream (one end) of the second wiring Cm. For example, when the third switching element SW3 is shared, one third switching element SW3 is provided upstream (one end) of the third wiring Rp.

[0031] 2 is a cross-sectional view of a main part 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 taken along the xz plane passing through the center of the width of the domain wall motion layer 30 in the y direction.

[0032] 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 region S and a drain region D formed in a substrate Sub. The substrate Sub is, for example, a semiconductor substrate. The third switching element SW3 is electrically connected to the third wiring Rp and is, for example, shifted in the y direction in Fig. 2.

[0033] 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 In.

[0034] The insulating layer In is an insulating layer that insulates between the wires of the multilayer wiring and between the elements. The domain wall motion element 100 and the transistor Tr are electrically isolated by the insulating layer In, except for the wires w1 and w2. The insulating layer In 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 (Al2O3), aluminum oxynitride (AlON), aluminum nitride (AlN), zirconium oxide (ZrO x ) etc.

[0035] Although FIG. 2 shows an example in which the domain wall motion element 100 is located above the substrate Sub with the insulating layer In sandwiched therebetween, the domain wall motion element 100 may be located on the substrate Sub.

[0036] [Magnetic domain wall motion element] FIG. 3 is a cross-sectional view of the domain wall motion element 100 according to the first embodiment. The domain wall motion element 100 has a laminate 1, a first surface layer 50, a first conductive layer 60, and a second conductive layer 70 stacked above a substrate Sub. The first surface layer 50 is stacked on at least a portion of the upper surface of the laminate 1. The first conductive layer 60 and the second conductive layer 70 are stacked on at least a portion of the upper surface of the laminate 1. The laminate 1 has a ferromagnetic layer 10, a non-magnetic layer 20, and a domain wall motion layer 30. FIG. 3 is a cross-sectional view of the domain wall motion element 100 cut along an xz plane that passes through the center of the domain wall motion layer 30 in the y direction. One example of the domain wall motion element 100 is a memory element.

[0037] "Ferromagnetic layer" The ferromagnetic layer 10 faces the nonmagnetic layer 20. The ferromagnetic layer 10 has a magnetization M oriented in one direction. 10The magnetization M of the ferromagnetic layer 10 10 is the magnetization M of the domain wall displacement layer 30 when a predetermined external force is applied. 33A , M 33B The orientation direction is less likely to change than in the case of the magnetization M. The predetermined external force is, for example, an external force applied to the magnetization by an external magnetic field or an external force applied to the magnetization by a spin-polarized current. The ferromagnetic layer 10 is sometimes called a magnetization fixed layer or a magnetization reference layer. 10 is oriented in the +z direction, for example. In this embodiment, the ferromagnetic layer 10 may be referred to as a first ferromagnetic layer.

[0038] Although the following description will be given using an example in which the magnetization is oriented in the z-axis direction, the magnetization of the domain wall motion layer 30 and the ferromagnetic layer 10 may be oriented in any direction within the xy plane. When the magnetization is oriented in the z direction, the power consumption of the domain wall motion device 100 and the heat generation during operation are reduced compared to when the magnetization is oriented in the xy plane. Furthermore, when the magnetization is oriented in the z direction, the movement width of the domain wall DW when a pulse current of the same intensity is applied is smaller than when the magnetization is oriented in the xy plane. On the other hand, when the magnetization is oriented in any direction within the xy plane, the magnetoresistance change width (MR ratio) of the domain wall motion device 100 is larger than when the magnetization is oriented in the z direction.

[0039] The ferromagnetic layer 10 includes a ferromagnetic material. Examples of ferromagnetic materials that can be used to form the ferromagnetic layer 10 include metals selected from the group consisting of Cr, Mn, Co, Fe, and Ni, alloys containing one or more of these metals, and alloys containing these metals and at least one of B, C, and N. Examples of the ferromagnetic layer 10 include Co—Fe, Co—Fe—B, and Ni—Fe.

[0040] The material constituting the ferromagnetic layer 10 may be a Heusler alloy. Heusler alloys are half-metallic and have high spin polarization. Heusler alloys are intermetallic compounds with a chemical composition of XYZ or X2YZ, where X is a transition metal element or a noble metal element of the Co, Fe, Ni, or Cu group on the periodic table, Y is a transition metal element or an element species of X of the Mn, V, Cr, or Ti group, and Z is a typical element of groups III to V. Examples of Heusler alloys include Co2FeSi, Co2FeGe, Co2FeGa, Co2MnSi, and Co2Mn 1-a Fe a Al b Si 1-b , Co2FeGe 1-c Ga c etc.

[0041] The thickness of the ferromagnetic layer 10 may be 1.5 nm or less, or 1.0 nm or less, when the easy axis of magnetization of the ferromagnetic layer 10 is set to the z direction (to form a perpendicular magnetization film). When the thickness of the ferromagnetic layer 10 is reduced, perpendicular magnetic anisotropy (interface perpendicular magnetic anisotropy) is imparted to the ferromagnetic layer 10 at the interface between the ferromagnetic layer 10 and another layer (non-magnetic layer 20), making it easier for the magnetization of the ferromagnetic layer 10 to be oriented in the z direction.

[0042] When the easy axis of magnetization of ferromagnetic layer 10 is set to the z direction (to form a perpendicular magnetization film), ferromagnetic layer 10 may be a laminate of a ferromagnetic material selected from the group consisting of Co, Fe, and Ni and a non-magnetic material selected from the group consisting of Pt, Pd, Ru, and Rh, and an intermediate layer selected from the group consisting of Ir and Ru may be inserted at any position in the laminate. Stacking a ferromagnetic material and a non-magnetic material can impart perpendicular magnetic anisotropy, and inserting an intermediate layer makes it easier to orient the magnetization of ferromagnetic layer 10 in the z direction.

[0043] "Domain wall displacement layer" The domain wall displacement layer 30 is, for example, rectangular in shape with its major axis in the x direction and its minor axis in the y direction when viewed from above in the z direction. The domain wall displacement layer 30 is a magnetic layer that faces the ferromagnetic layer 10 with the nonmagnetic layer 20 sandwiched between them. The domain wall displacement layer 30 is a layer that can magnetically record information by changing the internal magnetic state.

[0044] The domain wall displacement layer 30 has magnetization fixed regions 31 and 32 and a domain wall displacement region 33. The domain wall displacement region 33 is sandwiched between the two magnetization fixed regions 31 and 32.

[0045] The magnetization fixed region 31 is a region of the domain wall displacement layer 30 that overlaps with the first conductive layer 60 when viewed from the z direction. The magnetization fixed region 32 is a region of the domain wall displacement layer 30 that overlaps with the second conductive layer 70 when viewed from the z direction. The magnetization M of the magnetization fixed regions 31 and 32 31 , M 32 is the magnetization M of the first magnetic domain 33A and the second magnetic domain 33B of the domain wall motion region 33 described later. 33A , M 33B The magnetization reversal is more difficult, and the magnetization M 33A , M 33B Therefore, the magnetization M of the magnetization fixed regions 31 and 32 is not reversed even when an external force of a threshold value at which the magnetization M is reversed is applied. 31 , M 32 is the magnetization M of the domain wall motion region 33 33A , M 33B is said to be fixed relative to

[0046] Magnetization M of the magnetization fixed region 31 31 and the magnetization M of the magnetization fixed region 32 32 The magnetization M of the magnetization fixed region 31 is oriented in a direction different from that of the 31 and the magnetization M of the magnetization fixed region 32 32 The magnetization M of the magnetization fixed region 31 is oriented in the opposite direction. 31 is oriented in the +z direction, for example, and the magnetization M of the magnetization fixed region 32 32 is oriented in the −z direction, for example.

[0047] The domain wall motion region 33 is composed of a first magnetic domain 33A and a second magnetic domain 33B. The first magnetic domain 33A is adjacent to the magnetization fixed region 31. The magnetization M of the first magnetic domain 33A is 33A is the magnetization M of the magnetization fixed region 31 31 For example, the magnetization M of the magnetization fixed region 31 31 The second magnetic domain 33B is adjacent to the magnetization fixed region 32. The magnetization M of the second magnetic domain 33B 33Bis the magnetization M of the magnetization fixed region 32 32 For example, the magnetization M of the magnetization fixed region 32 32 Therefore, the magnetization M of the first magnetic domain 33A 33A and the magnetization M of the second magnetic domain 33B 33B are oriented in the opposite direction (antiparallel).

[0048] The boundary between the first magnetic domain 33A and the second magnetic domain 33B is the domain wall DW. The domain wall DW moves within the domain wall motion region 33. In principle, the domain wall DW does not intrude into the magnetization fixed regions 31 and 32.

[0049] The domain wall motion element 100 can record data in multiple values ​​or continuously depending on the position of the domain wall DW of the domain wall motion layer 30. The data recorded in the domain wall motion layer 30 is read out as a change in the resistance value of the domain wall motion element 100 when a read current is applied.

[0050] The ratio of the first magnetic domain 33A to the second magnetic domain 33B in the domain wall motion region 33 changes when the domain wall DW moves. When the domain wall DW moves in the +x direction and the area of ​​the first magnetic domain 33A increases in plan view from the z direction, the resistance value of the domain wall motion element 100 decreases. Conversely, when the domain wall DW moves in the -x direction and the area of ​​the second magnetic domain 33B increases in plan view from the z direction, the resistance value of the domain wall motion element 100 increases.

[0051] The domain wall DW moves by applying a write current in the x direction of the domain wall motion region 33. For example, when a write current (for example, a current pulse) in the +x direction is applied to the domain wall motion region 33, electrons flow in the -x direction, which is opposite to the current, and therefore the domain wall DW moves in the -x direction. When a current flows from the first magnetic domain 33A to the second magnetic domain 33B, electrons spin-polarized in the second magnetic domain 33B are magnetized by the magnetization M of the first magnetic domain 33A. 33A The magnetization of the first magnetic domain 33A is reversed. 33A When the magnetization of is reversed, the domain wall DW moves in the -x direction.

[0052] The domain wall displacement layer 30 is made of a magnetic material. The domain wall displacement layer 30 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 30 include a Co and Ni stacked film, a Co and Pt stacked film, a Co and Pd stacked film, an MnGa-based material, a GdCo-based material, and a TbCo-based material. Ferrimagnetic materials such as MnGa-based materials, GdCo-based materials, and TbCo-based materials have low saturation magnetization, which reduces the threshold current required to move the domain wall DW. Furthermore, a Co and Ni stacked film, a Co and Pt stacked film, and a Co and Pd stacked film have high coercivity, which reduces the domain wall DW movement speed.

[0053] The easy axis of magnetization of the domain wall displacement layer 30 is preferably set to intersect with the plane in which the domain wall displacement layer 30 extends. That is, it is preferable that the easy axis of magnetization of the domain wall displacement layer 30 be set to the z direction (to be a perpendicular magnetization film). When the domain wall displacement layer 30 is a perpendicular magnetization film, the domain wall DW can be driven with a low current.

[0054] "Nonmagnetic layer" The non-magnetic layer 20 is located between the ferromagnetic layer 10 and the domain wall displacement layer 30. The non-magnetic layer 20 is stacked on one surface of the domain wall displacement layer 30.

[0055] The nonmagnetic layer 20 is made of, for example, a nonmagnetic insulator, semiconductor, or metal. Examples of nonmagnetic insulators include Al2O3, SiO2, MgO, MgAl2O4, and materials in which part of the Al, Si, and Mg in these materials are substituted with Zn, Be, Ga, etc. These materials have a wide band gap and excellent insulating properties. When the nonmagnetic layer 20 is made of a nonmagnetic insulator, the nonmagnetic layer 20 is a tunnel barrier layer. Examples of nonmagnetic metals include Cu, Au, and Ag. Examples of nonmagnetic semiconductors include Si, Ge, CuInSe2, CuGaSe2, and Cu(In,Ga)Se2.

[0056] The thickness of the non-magnetic layer 20 is, for example, 20 Å or more, and may be 30 Å or more. If the thickness of the non-magnetic layer 20 is large, the resistance area area (RA) of the domain wall motion element 100 increases. The resistance area area (RA) of the domain wall motion element 100 is, for example, 1×10 5 Ωμm 2 That's 1 x 10 6 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 ​​the cross section obtained by cutting the nonmagnetic layer 20 in the xy plane).

[0057] "First surface layer" The first surface layer 50 is in contact with at least a portion of the top surface 30a of the domain wall displacement layer 30. For example, the first surface layer 50 is in contact with at least a portion of the first portion 30a1 of the top surface 30a. The first surface layer 50 may also be in contact with the entire first portion 30a1. FIG. 3 shows the state in which the first surface layer 50 is in contact with the entire first portion. The top surface 30a is the top surface of the domain wall displacement layer 30 in the z direction, and the first portion 30a1 is the portion of the top surface 30a between a first conductive layer 60 and a second conductive layer 70, which will be described later. The first surface layer 50 is sandwiched between the domain wall displacement layer 30 and the insulating layer In in the z direction, for example.

[0058] The first surface layer 50 is adjacent to the first conductive layer 60. The first surface layer 50 is sandwiched between the first conductive layer 60 and the second conductive layer 70 in the x direction, for example.

[0059] The resistivity of the first surface layer 50 is higher than the resistivity of the domain wall displacement layer 30. The resistivity of the first surface layer 50 may be, for example, two or more times or three or more times the resistivity of the domain wall displacement layer 30. The resistance value of the first surface layer 50a may be higher than the resistance value of the domain wall displacement layer 30. The resistance value of the first surface layer 50a may be, for example, two or more times or three or more times the resistance value of the domain wall displacement layer 30.

[0060] The first surface layer 50 is a layer containing a metal element or an alloy, and includes, for example, a metal selected from the group consisting of Bi, Ni, Cr, Ti, Zr, and W, or an alloy containing one or more of these metal elements. The first surface layer 50 may be a layer made of a metal element or an alloy. By including these metal elements or alloys, it is possible to further suppress the flow of current through the first surface layer 50. Furthermore, the current flowing through the domain wall displacement layer 30 can be reduced, allowing the domain wall DW to be driven stably.

[0061] Examples of alloys containing one or more metal elements selected from the group consisting of Bi, Ni, Cr, Ti, Zr, and W include manganin and nichrome. From the viewpoint of ease of manufacturing, it is preferable to use a metal rather than an alloy for the first surface layer 50. Furthermore, since the resistivity of an alloy varies depending on the composition ratio of multiple elements, it is preferable to use a metal rather than an alloy from the viewpoint of ease of controlling the resistivity.

[0062] The first surface layer 50 may contain microcrystalline or amorphous material. The first surface layer 50 may contain microcrystalline or amorphous material inside, or may contain microcrystalline or amorphous material on its surface. The first surface layer 50 may be microcrystalline or amorphous. When the first surface layer 50 contains microcrystalline or amorphous material, crystallization of the first surface layer 50 is suppressed. In other words, when the first surface layer 50 contains microcrystalline or amorphous material, the resistivity of the first surface layer 50 can be increased.

[0063] Microcrystals are crystals with a very small particle size. In this embodiment, microcrystals refer to those for which a diffraction pattern cannot be obtained by XRD (X-ray diffraction) but a diffraction pattern can be obtained by ED (electron diffraction). Furthermore, amorphous refers to those for which a diffraction pattern cannot be obtained by either XRD or ED. In this embodiment, both microcrystals and amorphous refer to X-ray amorphous, which cannot obtain a diffraction pattern by XRD but, for example, gives a continuous, broad peak.

[0064] Figure 4 shows the results of electron diffraction performed on microcrystals using a TEM (transmission electron microscope). Figure 5 shows the results of electron diffraction performed on amorphous material using a TEM. The white areas in Figures 4 and 5 are diffraction spots where diffracted light was detected.

[0065] Microcrystals have a crystalline structure. Therefore, as shown in Figure 4, electron diffraction of microcrystals produces diffraction spots associated with the crystalline structure. On the other hand, amorphous materials do not have a specific crystalline structure. Therefore, as shown in Figure 5, electron diffraction of amorphous materials produces a circular halo pattern, and no diffraction spots associated with the crystalline structure are observed. Note that when electron diffraction is performed on a single crystal, diffraction spots due to the crystalline structure are observed. The diffraction spots of a single crystal are not circular.

[0066] Reducing the area of ​​the cross section perpendicular to the y direction of the first surface layer 50 can reduce the resistance value of the first surface layer 50. For example, reducing the height (thickness) of the first surface layer 50 in the z direction can reduce the resistance value of the first surface layer 50. The thickness of the first surface layer 50 may be, for example, 2 nm or less, or 1 nm or less. Furthermore, by setting the thickness of the first surface layer 50 within this range, the first surface layer 50 is more likely to contain amorphous or microcrystalline matter.

[0067] "First conductive layer and second conductive layer" The first conductive layer 60 and the second conductive layer 70 are connected to at least a part of the top surface 30a of the domain wall displacement layer 30. The second conductive layer 70 is connected to the domain wall displacement layer 30 at a distance from the first conductive layer 60. The second conductive layer 70 is connected to, for example, the top surface 30a of the domain wall displacement layer 30. The second conductive layer 70 may be connected to a surface other than the top surface 30a, such as a side surface of the domain wall displacement layer 30. The first conductive layer 60 and the second conductive layer 70 are connected to, for example, a first end portion and a second end portion of the domain wall displacement layer 30. The first conductive layer 60, the second conductive layer 70 and the domain wall displacement layer 30 may be in direct contact with each other, or another layer may be interposed therebetween.

[0068] At least a portion of the first conductive layer 60 is sandwiched between the first surface layer 50 and the domain wall displacement layer 30. In Fig. 3, the sandwiching portion 61 of the first conductive layer 60 is sandwiched between the overlapping portion 51 of the first surface layer 50 and the domain wall displacement layer 30. At least a portion of the second conductive layer 70 is sandwiched, for example, between the first surface layer 50 and the domain wall displacement layer 30. In Fig. 3, the sandwiching portion 71 of the second conductive layer 70 is sandwiched between the overlapping portion 52 and the domain wall displacement layer 30. That is, the overlapping portion 51 and the sandwiching portion 61, and the overlapping portion 52 and the sandwiching portion 71, respectively, overlap in the z direction.

[0069] The length in the x direction of the overlapping portion 51 is, for example, less than 1 / 10 of the length in the x direction of the first conductive layer 60. The length in the x direction of the overlapping portion 52 is, for example, less than 1 / 10 of the length in the x direction of the second conductive layer 70.

[0070] The first conductive layer 60 and the second conductive layer 70 are made of a conductive material. The first conductive layer 60 and the second conductive layer 70 include, for example, a magnetic material. The first conductive layer 60 and the second conductive layer 70 include, 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 first conductive layer 60 and the second conductive layer 70 are, for example, Co-Fe, Co-Fe-B, Ni-Fe, etc.

[0071] Furthermore, when the magnetization easy axes of the first conductive layer 60 and the second conductive layer 70 are set in the z direction (perpendicular magnetization films), the first conductive layer 60 and the second conductive layer 70 may be a laminate of a ferromagnetic material selected from the group consisting of Co, Fe, and Ni and a non-magnetic material selected from the group consisting of Pt, Pd, Ru, and Rh. The first conductive layer 60 may also have a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure consists of two magnetic layers sandwiching a non-magnetic layer. The magnetization of each of the two magnetic layers is fixed, and the fixed magnetization directions are opposite to each other.

[0072] When the first conductive layer 60 contains a magnetic material, the magnetization M of the first conductive layer 60 60 is oriented in one direction. Magnetization M 60The first conductive layer 60 is oriented in the +z direction. 31 The magnetization M of the first conductive layer 60 is fixed. 60 and the magnetization M of the magnetization fixed region 31 31 For example, they are oriented in the same direction.

[0073] When the second conductive layer 70 contains a magnetic material, the magnetization M of the second conductive layer 70 70 is the magnetization M of the first conductive layer 60 60 The magnetization M 70 In this case, the second conductive layer 70 is oriented in the −z direction. 32 is fixed, and the magnetization M of the second conductive layer 70 70 and the magnetization M of the magnetization fixed region 32 32 When the second conductive layer 70 does not contain a magnetic material, the magnetization M of the magnetization fixed region 32 is oriented in the same direction. 32 is fixed by, for example, an external magnetic field.

[0074] Here, an example is presented in which both the first conductive layer 60 and the second conductive layer 70 are magnetic. The first conductive layer 60 and the second conductive layer 70 do not have to be magnetic. If the first conductive layer 60 and the second conductive layer 70 are not magnetic, the current density in the domain wall displacement layer 30 decreases sharply at the portions in contact with the first conductive layer 60 and the second conductive layer 70, thereby limiting the displacement range of the domain wall DW to within the domain wall displacement region 33.

[0075] When the easy magnetization direction of the first conductive layer 60, the second conductive layer 70, and the domain wall displacement layer 30 is set to the z direction (to form a perpendicular magnetization film), the magnetization M of the magnetization fixed regions 31 and 32 is 31 and M 32 The direction can be fixed in the z direction.

[0076] The magnetization direction of each layer of the domain wall motion device 100 can be confirmed by, for example, measuring a magnetization curve. The magnetization curve can be measured using, for example, MOKE (Magnetic Optical Kerr Effect). Measurement using MOKE is a measurement method in which polarized light is directly incident on the object to be measured and the magneto-optical effect (magnetic Kerr effect) is used to cause the rotation of the polarization direction.

[0077] Next, a method for manufacturing the domain wall motion element 100 will be described. The domain wall motion element 100 is formed by a process of stacking each layer and a process of processing a part of each layer into a predetermined shape. The layers can be stacked by sputtering, chemical vapor deposition (CVD), electron beam evaporation (EB evaporation), atomic laser deposition, or the like. The layers can be processed by photolithography, ion milling, or the like.

[0078] First, a ferromagnetic layer, a nonmagnetic layer, a domain wall displacement layer, and a conductive layer are stacked in this order above the substrate Sub. Next, unnecessary portions of these layers are removed in the x and y directions using, for example, photolithography, and each layer is processed into a predetermined shape. The ferromagnetic layer becomes the ferromagnetic layer 10, the nonmagnetic layer becomes the nonmagnetic layer 20, and the domain wall displacement layer becomes the domain wall displacement layer 30. Next, the conductive layer is removed, except for two portions overlapping the ends of the domain wall displacement layer 30, using, for example, ion milling. That is, the portion of the upper surface 30a of the domain wall displacement layer 30 corresponding to the first portion 30a1 is exposed. This process results in the conductive layer becoming the first conductive layer 60 and the second conductive layer 70. Next, a first surface layer 50 is stacked on the first portion 30a1. The upper surfaces of the first surface layer, the first conductive layer 60, and the second conductive layer 70 may then be covered with an insulating layer In. That is, the domain wall motion element 100 may include an insulating layer In in contact with the upper surface of the first surface layer 50. In this manner, the domain wall motion element 100 shown in Fig. 3 is obtained. The magnetic array 200 shown in Figs. 1 and 2 is manufactured using the method for manufacturing the domain wall motion element 100 according to this embodiment and a known method for manufacturing a magnetic array.

[0079] The domain wall motion device 100 according to the first embodiment can stabilize the motion of the domain wall DW. The motion of the domain wall DW refers to the controllability of the domain wall DW, such as the ease with which the domain wall DW moves. When the controllability of the domain wall DW is improved, malfunctions such as erroneous writing can be prevented, improving the reliability of the domain wall motion device 100. The reason why the domain wall motion device 100 according to this embodiment can achieve the above-mentioned effects will be explained using a comparative example.

[0080] 6 is a cross-sectional view of a domain wall motion element 300 according to a comparative example. The domain wall motion element 300 according to the comparative example is a bottom-pin type domain wall motion element. The domain wall motion element 300 according to the comparative example differs from the domain wall motion element 100 according to the first embodiment in that it does not have the first surface layer 50 and an insulating layer In' contacts the first portion 30a1'. In the domain wall motion element 300, the same components as those in the domain wall motion element 100 are designated by the same reference numerals and will not be described again.

[0081] In the manufacturing process of the domain wall motion element 300, the insulating layer In' is formed after the domain wall motion layer 30' is formed. The insulating layer In' is made of silicon oxide (SiO x ), silicon nitride (SiN x ), silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO x ), etc., the upper surface 30a' of the domain wall displacement layer 30' may be oxidized or nitrided in the process of forming the insulating layer In'. Furthermore, in the process of forming the insulating layer In', defects may occur in the upper surface 30a' of the domain wall displacement layer 30'. That is, the first portion 30a1' of the upper surface 30a' may contain impurities such as oxides or nitrides, or defects.

[0082] Impurities and defects in the domain wall motion layer 30' are factors that trap the domain wall DW. If a trapping factor exists in the domain wall motion layer 30', the domain wall DW may be strongly trapped in the vicinity of the trapping factor. If the domain wall DW is strongly trapped, the domain wall DW will not move smoothly even if a current of a predetermined current density is applied to the domain wall motion layer 30'. In other words, the domain wall motion element 300 requires sufficient energy to move the domain wall DW even when the domain wall DW is trapped by a defect or the like, and will not operate stably unless a current equal to or greater than the reversal current density is applied.

[0083] In contrast, in the domain wall motion element 100 according to the first embodiment, the first surface layer 50 is in contact with at least a portion of the top surface 30a of the domain wall motion layer 30. Therefore, in the domain wall motion element 100, the insulating layer In is formed after the first surface layer 50 is formed. Therefore, during the manufacturing process of the domain wall motion element 100, the generation of impurities such as oxides and nitrides and defects on the top surface 30a is suppressed. Therefore, in the domain wall motion element 100 according to the first embodiment, the generation of trapping factors in the domain wall motion layer 30 can be suppressed.

[0084] Therefore, in the domain wall motion device 100 according to the first embodiment, the movement of the domain wall DW can be stabilized.

[0085] Furthermore, in the domain wall motion element 100 according to the first embodiment, the domain wall motion layer, the first conductive layer, and the second conductive layer can be stacked together, which stabilizes the magnetic coupling between the domain wall motion layer 30 and the first conductive layer 60 and the second conductive layer 70. Furthermore, in the domain wall motion element 100 according to the first embodiment, the sandwiching portions 61 and 71 can be prevented from being oxidized or nitridized by the insulating layer In.

[0086] The resistivity of the first surface layer 50 is higher than the resistivity of the domain wall motion layer 30. Therefore, in the domain wall motion element 100, when a write current is applied to the domain wall motion layer 30 in the x direction, it is possible to prevent the current from being shunted to the first surface layer 50.

[0087] [First Modification] 7 is a cross-sectional view of a domain wall motion element 101 according to a first modification. The domain wall motion element 101 differs from the domain wall motion element 100 according to the first embodiment in the shapes of the first surface layer 50a, the first conductive layer 60a, and the second conductive layer 70a. In the domain wall motion element 101, the same components as those in the domain wall motion element 100 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0088] 7, at least a part of the first surface layer 50a is sandwiched between the first conductive layer 60a and the domain wall motion layer 30. In addition, at least a part of the first surface layer 50a is sandwiched between the second conductive layer 70a and the domain wall motion layer 30.

[0089] To manufacture the domain wall motion element 101, for example, a ferromagnetic layer, a nonmagnetic layer, a domain wall motion layer, and a surface layer are first stacked in this order on a substrate Sub and an insulating layer In. Next, unnecessary portions of these layers in the x and y directions are removed by photolithography. Next, two portions of the surface layer that overlap the ends of the domain wall motion layer 30 are removed by, for example, ion milling. That is, the portions of the upper surface 30a of the domain wall motion layer 30 that correspond to the ends are exposed. This process turns the surface layer into a first surface layer 50a. Next, a conductor is filled into the exposed ends of the domain wall motion layer 30 to form a first conductive layer 60a and a second conductive layer 70a. Next, the first surface layer 50a, the first conductive layer 60a, and the second conductive layer 70a may be covered with an insulating layer In. The difference in shape between the first conductive layer 60 and the second conductive layer 70 of the domain wall motion element 100 and the first conductive layer 60a and the second conductive layer 70a of the domain wall motion layer 101 is due to the difference in the order of the manufacturing processes.

[0090] The domain wall motion device 101 according to the first modification also provides the same effects as the domain wall motion device 100 according to the first embodiment. In particular, in the domain wall motion device 101, the first surface layer 50a is formed before the first conductive layer 60a and the second conductive layer 70a, so that the first portion 30a1 of the upper surface 30a of the domain wall motion layer 30 can be prevented from becoming rough due to ion milling. Therefore, in modification 1, the surface of the upper surface 30a of the domain wall motion layer 30 can be smoothed. This makes it possible to further stabilize the movement of the domain wall DW.

[0091] Furthermore, in the domain wall motion element 101, after the surface layer is deposited, portions of the surface layer corresponding to the first conductive layer 60a and the second conductive layer 70a are removed by ion milling or the like, and then the first conductive layer 60a and the second conductive layer 70a are formed. Therefore, the surfaces of the domain wall motion layer 30a that contact the first conductive layer 60a and the second conductive layer 70a are rougher than the first portion 30a1. When the surfaces of the domain wall motion layer 30a that contact the first conductive layer 60a and the second conductive layer 70a are rougher, the domain wall DW is more easily fixed in the magnetization fixed regions 31 and 32. In other words, the domain wall DW can be further prevented from penetrating the magnetization fixed regions 31 and 32.

[0092] 7 shows an example in which at least a portion of the first conductive layer 60a and the first surface layer 50a and at least a portion of the second conductive layer 70a and the first surface layer 50a overlap in the z direction, but the present invention is not limited to this example. For example, the first surface layer 50a may not overlap the first conductive layer 60a and the second conductive layer 70a in the z direction.

[0093] [Second Modification] 8 is a cross-sectional view of a domain wall motion element 102 according to the second modification. The domain wall motion element 102 differs from the domain wall motion element 100 according to the first embodiment in that it has second surface layers 53 and 54. The second surface layers 53 and 54 contact the top surface 62 of the first conductive layer 60 and the top surface 72 of the second conductive layer 70. 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 descriptions thereof will be omitted.

[0094] The second surface layers 53, 54 can be made of the same material as the first surface layer 50. The resistivity of the second surface layers 53, 54 is higher than that of the domain wall displacement layer 30, for example. The resistivity of the second surface layers 53, 54 may be two or more times or three or more times that of the domain wall displacement layer 30. The second surface layers 53, 54 may be formed on at least a portion of the upper surfaces 62, 72, respectively, or may be formed on the entire upper surfaces 62, 72, respectively.

[0095] The domain wall motion element 102 is manufactured, for example, by forming the domain wall motion element 101, then forming a hole in the insulating layer In at a position that overlaps with the first conductive layer 60 or the second conductive layer 70, and filling the hole in the same manner as the first surface layer 50a. Alternatively, the second surface layers 53 and 54 may be stacked and then covered with the insulating layer In.

[0096] The domain wall motion device 102 according to the second modification can also obtain the same effects as the domain wall motion device 100 according to the first embodiment. Furthermore, in the domain wall motion device 102, the upper surfaces 62, 72 of the first conductive layer 60 and the second conductive layer 70 can be prevented from being oxidized or nitrided. Therefore, the magnetization M of the magnetization fixed regions 31, 32 is prevented by the first conductive layer 60 and the second conductive layer 70. 31 ,M 32 That is, the domain wall DW can be further prevented from penetrating into the magnetization fixed regions 31 and 32.

[0097] [Third Modification] FIG. 9 is a cross-sectional view of a domain wall motion element 103 according to a third modification. The domain wall motion element 103 differs from the domain wall motion element 102 in that it includes third surface layers 56 and 57 in contact with the side surfaces of the first conductive layer 60 and the second conductive layer 70. In the domain wall motion element 103, components similar to those in the domain wall motion element 102 are denoted by the same reference numerals, and their description will be omitted. FIG. 9 illustrates an example in which the third surface layers 56 and 57 are formed on both side surfaces of the first conductive layer 60 and the second conductive layer 70, but it is sufficient that the third surface layers 56 and 57 are formed on at least one side surface of the first conductive layer 60 and the second conductive layer 70. Note that while FIG. 9 illustrates an example in which the first surface layer 50, the second surface layers 53 and 54, and the third surface layers 56 and 57 are integral, they may also be configured as independent layers spaced apart from each other.

[0098] The third surface layers 56, 57 can be made of the same material as the first surface layer 50. The resistivity of the third surface layers 56, 57 is higher than the resistivity of the domain wall displacement layer 30. The resistivity of the third surface layers 56, 57 may be two or more times or three or more times the resistivity of the domain wall displacement layer 30. The third surface layers 56, 57 may be formed on both side surfaces in the x direction of the first conductive layer 60 and the second conductive layer 70, respectively, or may be formed on one side surface.

[0099] The domain wall motion element 103 according to the third modification is manufactured using, for example, the same method as the domain wall motion element 100 according to the first embodiment. That is, the domain wall motion element 103 is manufactured by forming the first conductive layer 60 and the second conductive layer 70, then forming a surface layer on the first conductive layer 60, the second conductive layer 70, and the first portion 30a1 of the domain wall motion layer 30, and then covering them with an insulating layer In.

[0100] The domain wall motion device 103 according to the third modification can also obtain the same effects as the domain wall motion device 100 according to the first embodiment. Furthermore, in the domain wall motion device 103, the insulating layer In can prevent the side surfaces of the first conductive layer 60 and the second conductive layer 70 from being oxidized or nitrided. Therefore, the first conductive layer 60 and the second conductive layer 70 can prevent the magnetization M of the magnetization fixed regions 31 and 32 from being oxidized or nitrided. 31 ,M 32 That is, the domain wall DW can be further prevented from penetrating into the magnetization fixed regions 31 and 32.

[0101] [Fourth Modification] 10 is a cross-sectional view of a domain wall motion element 104 according to a fourth modified example. The domain wall motion element 104 differs from the domain wall motion element 100 in that at least a part of the first surface layer 50b is sandwiched between the first conductive layer 60b, the second conductive layer 70b and the domain wall motion layer 30. 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 will not be described.

[0102] The first surface layer 50b may be formed over the entire area that overlaps with the first conductive layer 60b and the second conductive layer 70b when viewed in a plane from the z direction, or may be formed to include a portion of the area that overlaps with the first conductive layer 60b and the second conductive layer 70b.

[0103] The first surface layer 50b can be made of the same material as the first surface layer 50. The first conductive layer 60b and the second conductive layer 70b are connected to the domain wall displacement layer 30, respectively.

[0104] The first conductive layer 60b and the second conductive layer 70b have thicknesses in the z direction smaller than the first conductive layer 60 and the second conductive layer 70, respectively.

[0105] The domain wall motion element 104 according to the fourth modification also provides the same effects as the domain wall motion element 100 according to the first embodiment.

[0106] [Variation 5] 11 is a cross-sectional view of a domain wall motion element 105 according to Modification 5. The domain wall motion element 105 differs from the domain wall motion element 100 in that it does not have the second conductive layer 70. 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 the description thereof will be omitted.

[0107] The domain wall motion element 105 has only one first conductive layer 60. The magnetization fixed region 32 of the domain wall motion element 105 is fixed by, for example, an external magnetic field.

[0108] Furthermore, the domain wall motion element 105 does not necessarily have to have the magnetization fixed region 32. In the domain wall motion element 105 that does not have the magnetization fixed region 32, the movement of the domain wall DW can be controlled by controlling the magnitude of the current pulse to be applied.

[0109] The domain wall motion device 105 according to this embodiment can also obtain the same effects as the domain wall motion device 100 according to the first embodiment. That is, as with the domain wall motion device 105, if it has at least one conductive layer, it is possible to stabilize the movement of the domain wall DW.

[0110] Although FIG. 11 shows an example in which the domain wall motion element 105 has only the first conductive layer 60, it may have only the second conductive layer .

[0111] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as set forth in the claims.

[0112] For example, the characteristic configurations of the first embodiment and the first to fifth modifications may be combined. [Explanation of symbols]

[0113] 1: laminate, 10: ferromagnetic layer, 20: non-magnetic layer, 30: domain wall displacement layer, 30a: upper surface, 31, 32: magnetization fixed region, 33: domain wall displacement region, 33A: first magnetic domain, 33B: second magnetic domain, 50: first surface layer, 60: first conductive layer, 70: second conductive layer, DW: domain wall, In: insulating layer

Claims

1. a laminate located above a substrate, the laminate having a ferromagnetic layer, a non-magnetic layer, and a domain wall displacement layer, which are laminated in this order from the side closest to the substrate, a first conductive layer, a first surface layer, and a second conductive layer disposed apart from the first conductive layer in an extension direction of the domain wall displacement layer; the nonmagnetic layer is sandwiched between the ferromagnetic layer and the domain wall displacement layer, the first conductive layer is connected to an upper surface of the domain wall displacement layer, the first surface layer is in contact with an entire region between the first conductive layer and the second conductive layer in a plan view of the upper surface of the domain wall displacement layer, the resistivity of the first surface layer is higher than the resistivity of the domain wall displacement layer, The first conductive layer and the second conductive layer each have a region sandwiched between the first surface layer and the domain wall motion layer.

2. a laminate located above a substrate, the laminate having a ferromagnetic layer, a non-magnetic layer, and a domain wall displacement layer, which are laminated in this order from the side closest to the substrate, a first conductive layer, a first surface layer, and a second conductive layer disposed apart from the first conductive layer in an extension direction of the domain wall displacement layer; the nonmagnetic layer is sandwiched between the ferromagnetic layer and the domain wall displacement layer, the first conductive layer is connected to an upper surface of the domain wall displacement layer, the first surface layer is in contact with an entire region between the first conductive layer and the second conductive layer in a plan view of the upper surface of the domain wall displacement layer, the resistivity of the first surface layer is higher than the resistivity of the domain wall displacement layer, a first second surface layer in contact with an upper surface of the first conductive layer, and a second second surface layer in contact with an upper surface of the second conductive layer, A domain wall motion element, wherein the resistivity of the first second surface layer and the resistivity of the second second surface layer are higher than the resistivity of the domain wall motion layer.

3. The domain wall motion element according to claim 1 , further comprising an insulating layer in contact with an upper surface of the first surface layer.

4. 4. The domain wall motion element according to claim 1, wherein the first surface layer is amorphous or microcrystalline.

5. 5. The domain wall motion element according to claim 1, wherein the first surface layer contains at least one element selected from the group consisting of Bi, Ni, Cr, Ti, Zr, and W.

6. 6. The domain wall motion element according to claim 1, wherein the direction of easy magnetization of said domain wall motion layer intersects with a plane in which said domain wall motion layer extends.

7. a first third surface layer in contact with a side surface of the first conductive layer and a second third surface layer in contact with a side surface of the second conductive layer, 3. The domain wall motion element according to claim 1, wherein the resistivity of the first third surface layer and the resistivity of the second third surface layer are higher than the resistivity of the domain wall motion layer.

8. A substrate and a plurality of domain wall motion elements according to any one of claims 1 to 7, A magnetic array, wherein a plurality of the domain wall motion elements are integrated on the substrate.

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