Domain wall moving element and magnetic array

Abstract

This invention provides a domain wall moving element and magnetic array with a high MR ratio and high domain wall controllability. The domain wall moving element of this embodiment includes: a magnetoresistive element having, sequentially from the side closest to the substrate, a reference layer, a non-magnetic layer, and a domain wall moving layer; a first magnetization fixing layer and a second magnetization fixing layer, respectively connected to and separated from the domain wall moving layer; the domain wall moving layer includes a ferromagnetic layer comprising multiple intercalation layers, the ferromagnetic layer containing Co and Fe, and having perpendicular magnetic anisotropy; during writing, a writing current flows along the domain wall moving layer between the first magnetization fixing layer and the second magnetization fixing layer.

Description

Technical Field

[0001] This invention relates to magnetic domain wall moving elements and magnetic arrays. Background Technology

[0002] The next generation of non-volatile memory, such as flash memory, which has reached the limit in miniaturization, is attracting much attention. Examples of next-generation non-volatile memory include MRAM (Magnetoresistive Random Access Memory), ReRAM (Resistive Random Access Memory), and PCRAM (Phase Change Random Access Memory).

[0003] MRAM utilizes the change in resistance caused by the change in the direction of magnetization in data recording. Data recording is performed by individual magnetoresistive elements constituting the MRAM. For example, Patent Document 1 describes a magnetoresistive element (domain wall moving element) that can record multi-valued data by moving the domain walls within a first ferromagnetic layer (domain wall moving layer). Patent Document 1 also describes how, by utilizing magnetic coupling with a second ferromagnetic layer group, magnetization-fixed regions can be easily formed at both ends of the first ferromagnetic layer.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2009 / 122990 Summary of the Invention

[0007] Domain wall moving elements capable of stably representing multiple states can be used for a variety of applications. One method to achieve this is to increase the resistance variation range (MR ratio) of the domain wall moving element. As the resistance variation range increases, multiple states can be distributed across the resistance variation range, thus stably representing multiple states.

[0008] Another method to achieve a domain wall moving element capable of stably representing multiple states is to improve the controllability of the domain wall movement. When the controllability of the domain wall is improved, multiple states can be distributed over the same resistance change amplitude, and multiple states can be stably represented.

[0009] On the other hand, it is difficult to realize a magnetic domain wall moving element with a large MR ratio and high controllability of the domain walls.

[0010] The present invention was made in view of the above-mentioned problems, and its object is to provide a magnetic domain wall moving element and a magnetic array with a large MR ratio and high controllability of the magnetic domain walls.

[0011] (1) The domain wall moving element of the first aspect comprises: a magnetoresistive effect element having a reference layer, a non-magnetic layer and a domain wall moving layer sequentially from the side close to the substrate; a first magnetization fixing layer and a second magnetization fixing layer respectively connected to the domain wall moving layer and separated from each other, the domain wall moving layer comprising a ferromagnetic layer including a plurality of insertion layers, the ferromagnetic layer comprising Co and Fe and having perpendicular magnetic anisotropy, and during writing, a writing current flows along the domain wall moving layer between the first magnetization fixing layer and the second magnetization fixing layer.

[0012] (2) In the above-mentioned domain wall moving element, the thickness of the first magnetization fixing layer and the second magnetization fixing layer may be different.

[0013] (3) In the magnetic domain wall moving element described above, the first magnetization fixing layer and the second magnetization fixing layer may each have alternating magnetic coupling layers and ferromagnetic layers, and the number of ferromagnetic layers contained in the first magnetization fixing layer is different from the number of ferromagnetic layers contained in the second magnetization fixing layer.

[0014] (4) In the above-mentioned domain wall moving element, the insertion layer may also contain any one selected from MgO, Mg-Al-O, Mg, W, Mo, Ta, Pd, and Pt.

[0015] (5) In the above-mentioned domain wall moving element, the insertion layer may also have a plurality of insertion regions dispersed in an island-like manner.

[0016] (6) In the magnetic domain wall moving element described above, the first insert layer closest to the non-magnetic layer may contain any one of W, Mo, Ta, Pd, and Pt, and any of the insert layers other than the first insert layer may contain MgO or Mg-Al-O.

[0017] (7) In the domain wall moving element described above, the first ferromagnetic layer, which is closest to the non-magnetic layer among the ferromagnetic layers contained in the domain wall moving layer, may be thicker than the other ferromagnetic layers contained in the domain wall moving layer.

[0018] (8) In the domain wall moving element described above, the insertion layer that is furthest from the non-magnetic layer among the insertion layers included in the domain wall moving layer may be thicker than the other insertion layers included in the domain wall moving layer.

[0019] (9) In the domain wall moving element described above, the lower surfaces of the first magnetization fixing layer and the second magnetization fixing layer may be located below the upper surface of the domain wall moving layer.

[0020] (10) In the above-mentioned domain wall moving element, a vertical magnetic induction layer may also be provided, which is located on the domain wall moving layer.

[0021] (11) In the magnetic domain wall moving element described above, the vertical magnetic induction layer may also contain any one selected from MgO, Mg-Al-O, Mg, W, Mo, Ta, Pd, and Pt.

[0022] (12) In the domain wall moving element described above, the vertical magnetic induction layer may be located at least one of the first magnetization fixing layer and the domain wall moving layer, and the second magnetization fixing layer and the domain wall moving layer.

[0023] (13) In the above-mentioned domain wall moving element, it may also have a first conductive layer connected to the first magnetization fixing layer and a second conductive layer connected to the second magnetization fixing layer, wherein the first conductive layer is fitted into a recess formed on the upper surface of the first conductive layer.

[0024] (14) The magnetic array of the second aspect has a plurality of magnetic domain wall moving elements as described above.

[0025] Among the aforementioned domain wall moving elements and magnetic arrays, the MR ratio is large, and the controllability of the domain walls is also high. Attached Figure Description

[0026] Figure 1 This is a structural diagram of the magnetic array in the first embodiment.

[0027] Figure 2 This is a cross-sectional view of a characteristic portion of the magnetic array according to the first embodiment.

[0028] Figure 3 This is a cross-sectional view of the magnetic domain wall moving element according to the first embodiment.

[0029] Figure 4 This is a top view of the magnetic domain wall moving element of the first embodiment.

[0030] Figure 5 This is a cross-sectional view of the magnetic domain wall moving element according to the second embodiment.

[0031] Figure 6 This is a cross-sectional view of the magnetic domain wall moving element according to the third embodiment.

[0032] Figure 7This is a cross-sectional view of the domain wall moving element according to the fourth embodiment.

[0033] Figure 8 This is a cross-sectional view of the domain wall moving element according to the fifth embodiment.

[0034] Figure 9 This is a cross-sectional view of the domain wall moving element according to the sixth embodiment.

[0035] Figure 10 This is a cross-sectional view of a modified example of the magnetic domain wall moving element according to the sixth embodiment.

[0036] Figure 11 This is a cross-sectional view of the magnetic domain wall moving element according to the seventh embodiment. Detailed Implementation

[0037] The present embodiment will now be described in detail with appropriate reference to the accompanying drawings. To facilitate understanding of the features of the present invention, the drawings used in the following description sometimes show enlarged features, and the dimensions and ratios of the constituent elements may differ from the actual dimensions. The materials, dimensions, etc., illustrated in the following description are examples, and the present invention is not limited thereto; appropriate modifications can be made to implement the invention within the scope of its implementation.

[0038] First, the directions are defined. The x-direction and y-direction are related to the substrate Sub described below (refer to...). Figure 2 The x-direction is approximately parallel to one side of the magnetic domain wall moving layer. The y-direction is orthogonal to the x-direction. The z-direction is the direction from the substrate Sub towards the magnetic domain wall moving element. In this specification, the +z direction is sometimes referred to as "up" and the -z direction as "down," but these expressions are for convenience and do not specify the direction of gravity. Furthermore, in this specification, "extending in the x-direction" means, for example, that the dimension in the x-direction is larger than the smallest of the dimensions in the x, y, and z directions. The same applies to extensions in other directions.

[0039] [First Implementation Method]

[0040] Figure 1 This is a structural diagram of the magnetic array according to the first embodiment. The magnetic array 200 includes: a plurality of domain wall moving 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 magnetic memories, multiplier units, neuromorphic devices, spin memories, and magneto-optical elements.

[0041] <First wiring, second wiring, third wiring>

[0042] The first wiring Wp is the write wiring. The first wiring Wp electrically connects the power supply and one or more domain wall moving elements 100. The power supply is connected to one end of the magnetic array 200 during use.

[0043] The second wiring Cm is a common wiring. The common wiring is used for both writing and reading data. The second wiring Cm electrically connects a reference potential and one or more domain wall moving elements 100. The reference potential is, for example, ground. The second wiring Cm can be individually provided on multiple domain wall moving elements 100, or it can be provided across multiple domain wall moving elements 100.

[0044] The third wiring Rp is the readout wiring. The third wiring Rp electrically connects the power supply and one or more magnetic domain wall moving elements 100. The power supply is connected to one end of the magnetic array 200 during use.

[0045] <First switching element, second switching element, third switching element>

[0046] exist Figure 1 In this configuration, each of the multiple domain wall moving elements 100 is connected to a first switching element SW1, a second switching element SW2, and a third switching element SW3. The first switching element SW1 is connected between the domain wall moving element 100 and the first wiring Wp. The second switching element SW2 is connected between the domain wall moving element 100 and the second wiring Cm. The third switching element SW3 is connected between the domain wall moving element 100 and the third wiring Rp.

[0047] 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, which are connected to the designated domain wall moving 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, which are connected to the designated domain wall moving element 100.

[0048] The first switching element SW1, the second switching element SW2, and the third switching element SW3 are elements that control the flow of current. These elements can be, for example, transistors and Ovonic Threshold Switches (OTS) that utilize crystal layer phase transitions; metal-insulator transition (MIT) switches that utilize band structure changes; Zener diodes and avalanche diodes that utilize breakdown voltage; or elements whose conductivity changes with atomic positions.

[0049] Any one of the first switching element SW1, the second switching element SW2, and the third switching element SW3 can be shared by the domain wall moving element 100 connected to the same wiring. For example, if the first switching element SW1 is shared, a first switching element SW1 is provided upstream (at one end) of the first wiring Wp. For example, if the second switching element SW2 is shared, a second switching element SW2 is provided upstream (at one end) of the second wiring Cm. For example, if the third switching element SW3 is shared, a third switching element SW3 is provided upstream (at one end) of the third wiring Rp.

[0050] Figure 2 This is a cross-sectional view of the main part of the magnetic array 200 in the first embodiment. Figure 2 It is cut off by the xz plane passing through the center of the y-direction width of the domain wall moving layer 10. Figure 1 The cross section obtained by a magnetic domain wall moving element 100.

[0051] Figure 2 The first switching element SW1 and the second switching element SW2 shown are transistors Tr. Transistor Tr has a gate electrode G, a gate insulating film GI, a source region S formed on a substrate Sub, and a drain region D. The substrate Sub is, for example, a semiconductor substrate. The third switching element SW3 is electrically connected to a third wiring Rp, for example, in... Figure 2 In the middle, it is located at a position deviated along the y-direction.

[0052] The individual transistors Tr and the domain wall moving elements 100 are electrically connected via wirings w1 and w2. Wirings w1 and w2 contain a conductive material. Wiring w1 is a through-hole wiring extending along the z-direction. Wiring w2 is an in-plane wiring extending in either direction within the xy-plane. Wirings w1 and w2 are formed within openings in the insulating layer In.

[0053] The insulating layer In is an insulating layer that insulates between wirings or components in a multilayer wiring system. The domain wall moving element 100 and the transistor Tr are electrically separated, except for wirings w1 and w2, by the insulating layer In. The insulating layer In is, for example, silicon oxide (SiO2). x ), silicon nitride (SiN) x Silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO2) x )wait.

[0054] exist Figure 2 The example shown is of a domain wall moving element 100 positioned above a substrate Sub with the insulating layer In between, but the domain wall moving element 100 may also be positioned on the substrate Sub.

[0055] "Magnetic domain wall moving element"

[0056] Figure 3 This is a cross-sectional view obtained by cutting the magnetic domain wall moving element 100 with the xz plane passing through the center of the y direction of the magnetic domain wall moving layer 10. Figure 4 This is a top view of the domain wall moving element 100 taken from the z-direction. The arrows shown in the figure are an example of the orientation direction of magnetization of the ferromagnetic material.

[0057] The domain wall moving element 100 is, for example, located on the electrode E that provides an electrical connection to the third wiring Rp. The domain wall moving element 100 includes, for example, a magnetoresistive element 40, a first magnetization fixing layer 50, and a second magnetization fixing layer 60. A first conductive layer 71 is connected to the first magnetization fixing layer 50, and a second conductive layer 72 is connected to the second magnetization fixing layer 60. The first conductive layer 71 and the second conductive layer 72 are... Figure 2 Part of the wiring w1. The domain wall moving element 100 is surrounded by an insulating layer In.

[0058] The magnetoresistive element 40 includes a domain wall moving layer 10, a non-magnetic layer 20, and a reference layer 30. The magnetoresistive element 40 is arranged in the order of reference layer 30, non-magnetic layer 20, and domain wall moving layer 10, starting from the side closest to the substrate Sub. When writing data to the magnetoresistive element 40, a write current flows between the first magnetization fixing layer 50 and the second magnetization fixing layer 60 along the domain wall moving layer 10. When reading data from the magnetoresistive element 40, a current is applied along the z-direction of the magnetoresistive element 40, and a readout current flows between the electrode E and the domain wall moving layer 10.

[0059] The domain wall moving layer 10 extends along the x-direction. The domain wall moving layer 10 has multiple magnetic regions internally, and domain walls (DWs) are located at the boundaries of these regions. The domain wall moving layer 10 is, for example, a layer that can magnetically record information through changes in magnetic state. The domain wall moving layer 10 is sometimes referred to as an analog layer or a magnetic recording layer.

[0060] The domain wall moving layer 10 has a first region A1, a second region A2, and a third region A3. The first region A1 is the region that overlaps with the first magnetization fixing layer 50 when viewed from the z-direction. The second region A2 is the region that overlaps with the second magnetization fixing layer 60 when viewed from the z-direction. The third region A3 is the region of the domain wall moving layer 10 other than the first region A1 and the second region A2. For example, the third region A3 is the region sandwiched between the first region A1 and the second region A2 in the x-direction.

[0061] The magnetization of the first region A1 is fixed by the magnetization of the first magnetization fixing layer 50. The magnetization of the second region A2 is fixed by the magnetization of the second magnetization fixing layer 60. "Magnetization is fixed" means that the magnetization does not reverse under the normal operation of the domain wall moving element 100 (without applying any external force beyond what is intended). For example, the orientation directions of the magnetization of the first region A1 and the second region A2 are opposite.

[0062] The third region A3 is a region where the direction of magnetization changes and the domain walls DW can move. The third region A3 has a first magnetic region A3a and a second magnetic region A3b. The magnetization orientations of the first magnetic region A3a and the second magnetic region A3b are opposite. The boundary between the first magnetic region A3a and the second magnetic region A3b is the domain wall DW. The magnetization of the first magnetic region A3a is, for example, oriented in the same direction as the magnetization of the first region A1. The magnetization of the second magnetic region A3b is, for example, oriented in the same direction as the magnetization of the adjacent second region A2. The domain walls DW, in principle, move within the third region A3 and do not intrude into the first region A1 or the second region A2.

[0063] When the ratio of the first magnetic region A3a to the second magnetic region A3b within the third region A3 changes, the domain wall DW moves. The domain wall DW moves by flowing 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, so the domain wall DW moves in the -x direction. When a current flows from the first magnetic region A3a to the second magnetic region A3b, the spin-biased electrons in the second magnetic region A3b cause a magnetization reversal in the first magnetic region A3a. This magnetization reversal in the first magnetic region A3a causes the domain wall DW to move in the -x direction.

[0064] The domain wall moving layer 10 has a ferromagnetic layer 11 and an insertion layer 12. The ferromagnetic layer 11 and the insertion layer 12 are stacked alternately. Adjacent ferromagnetic layers 11 are magnetically bonded to the insertion layer 12.

[0065] The ferromagnetic layer 11 contains Co and Fe. For example, the ferromagnetic layer 11 is a CoFe alloy. The ferromagnetic layer 11 can also be an alloy containing Co, Fe, and any one or more of the elements selected from B, C, and N. For example, the ferromagnetic layer 11 is Co-Fe-B.

[0066] The ferromagnetic layer 11 exhibits perpendicular magnetic anisotropy. Perpendicular magnetic anisotropy means that it has an easy magnetization axis in a direction that intersects (orthogonally) with the film surface. The thickness of each ferromagnetic layer 11 is, for example, less than 1.5 nm.

[0067] The ferromagnetic layer 11 is, for example, an alloy containing Co and Fe with a thickness of 1.5 nm or less. The Co and Fe alloy exhibits a larger magnetoresistance effect than laminates exhibiting perpendicular magnetic anisotropy, such as Co and Ni laminates, Co and Pt laminates, and Co and Pd laminates. Furthermore, if the Co and Fe alloy has a thickness of 1.5 nm or less, it exhibits a large magnetoresistance effect. When the magnetoresistance effect of the domain wall moving layer 10 is large, the MR ratio of the domain wall moving element 100 increases.

[0068] The thickness and material of the multiple ferromagnetic layers 11 can be the same or different.

[0069] The insertion layer 12 is located between the ferromagnetic layers 11. Through the effect of the interface between the insertion layer 12 and the ferromagnetic layers 11, the insertion layer 12 induces perpendicular magnetic anisotropy in the ferromagnetic layers 11.

[0070] The intercalation layer 12 comprises, for example, any material selected from MgO, Mg-Al-O, Mg, W, Mo, Ta, Pd, and Pt. These materials enhance the perpendicular magnetic anisotropy of the adjacent ferromagnetic layer 11. When the intercalation layer 12 is MgO or Mg-Al-O, the MR ratio of the domain wall moving element 100 is particularly improved. When the intercalation layer 12 is any material selected from Mg, W, Mo, Ta, Pd, and Pt, the resistance of the domain wall moving element 100 is reduced, and the power consumption is reduced. Furthermore, when the intercalation layer 12 is any material selected from Mo, Ta, Pd, and Pt, spin is injected into the ferromagnetic layer 11 through the spin Hall effect, and the magnetization of the ferromagnetic layer 11 is easily reversed. Mg-Al-O is an oxide of Mg and Al, meaning it is independent of the composition ratio. Mg-Al-O is, for example, MgAl2O4 with a spinel structure.

[0071] The thickness of the insertion layer 12 is, for example, less than 1 nm. By making the thickness of the insertion layer 12 sufficiently thin, the magnetic coupling of the adjacent ferromagnetic layers 11 is made sufficiently strong.

[0072] The materials of the multiple insertion layers 12 can be the same or different. For example, the first insertion layer 12A can also contain any material selected from W, Mo, Ta, Pd, and Pt, and any of the insertion layers 12 above the first insertion layer 12A can also contain MgO or Mg-Al-O. The first insertion layer 12A is the insertion layer closest to the non-magnetic layer 20 among the insertion layers 12. The domain wall moving element 100 is manufactured starting from the top. By placing the hard and difficult-to-machine MgO or Mg-Al-O on the upper part of the domain wall moving layer 10, the MgO or Mg-Al-O functions as an etching stop.

[0073] The insertion layer 12 can also be a layer in which a material selected from, for example, MgO, Mg-Al-O, Mg, W, Mo, Ta, Pd, and Pt is dispersed in an alloy containing Co and Fe. That is, the insertion layer 12 may be thin enough (at the atomic level) and may not constitute a complete layer. For example, the insertion layer 12 may also have multiple insertion regions containing a material selected from the above-mentioned material group dispersed in an island-like pattern in an alloy containing Co and Fe. These materials can enhance the perpendicular magnetic anisotropy of the insertion layer 12 and the adjacent ferromagnetic layer 11. The film thickness of the insertion layer 12 may be, for example, 1 nm or more. When the insertion layer 12 contains Co and Fe, even if the film thickness is relatively thick, the magnetic coupling with the adjacent ferromagnetic layer 11 is sufficiently strong.

[0074] The non-magnetic layer 20 is located between the magnetic domain wall moving layer 10 and the reference layer 30. The non-magnetic layer 20 is stacked on one side of the reference layer 30.

[0075] 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 some of the Al, Si, and Mg are replaced by Zn, Be, etc. These materials have large band gaps and excellent insulating properties. When the nonmagnetic layer 20 is made of a nonmagnetic insulator, it serves as a tunnel barrier layer. Examples of nonmagnetic metals include Cu, Au, Ag, etc. Examples of nonmagnetic semiconductors include Si, Ge, CuInSe₂, CuGaSe₂, Cu(In,Ga)Se₂, etc.

[0076] The thickness of the non-magnetic layer 20 is, for example, The above can also be used for The above applies. When the thickness of the non-magnetic layer 20 is relatively large, the resistivity-area product (RA) of the domain wall moving element 100 increases. The resistivity-area product (RA) of the domain wall moving element 100 is preferably 1 × 10⁻⁶. 4 Ωμm 2 The above is preferred, with 5×10 being more ideal. 4 Ωμm 2 The resistance-area product (RA) of the domain wall moving element 100 is expressed as the product of the element resistance of the domain wall moving element 100 and the element cross-sectional area of ​​the domain wall moving element 100 (the area of ​​the cut surface formed by cutting the non-magnetic layer 20 with the xy plane).

[0077] A non-magnetic layer 20 is sandwiched between a reference layer 30 and a domain wall moving layer 10. The reference layer 30 is located, for example, on electrode E. The reference layer 30 may also be stacked on a substrate Sub. The reference layer 30 is located at a position overlapping the domain wall moving layer 10 in the z-direction. The magnetization of the reference layer 30 is more difficult to reverse than the magnetization of the third region A3 of the domain wall moving layer 10. The magnetization of the reference layer 30 remains fixed in direction when an external force is applied that would reverse the magnetization of the third region A3. The reference layer 30 is sometimes referred to as a magnetization-fixed layer.

[0078] The reference layer 30 comprises a ferromagnetic material. For example, the reference layer 30 may contain a material that readily induces a coherent tunneling effect between itself and the domain wall moving layer 10. The reference layer 30 may contain, for example, a metal selected from Cr, Mn, Co, Fe, and Ni; an alloy containing one or more of these metals; or an alloy containing these metals and at least one of B, C, and N. The reference layer 30 may be, for example, Co-Fe, Co-Fe-B, or Ni-Fe.

[0079] Reference layer 30 can also be a Whistler alloy, for example. Whistler alloys are half-metals with high spin polarization. Whistler alloys are intermetallic compounds with a chemical composition of XYZ or X2YZ, where X is a transition metal or noble metal element of the Co, Fe, Ni, or Cu group in the periodic table; Y is a transition metal of the Mn, V, Cr, or Ti group or an element of X; and Z is a typical element of groups III to V. Examples of Whistler alloys include: Co2FeSi, Co2FeGe, Co2FeGa, Co2MnSi, and Co2Mn. 1－a Fe a Al b Si 1－b Co2FeGe 1－c Ga c wait.

[0080] Alternatively, the reference layer 30 can be a composite structure consisting of a ferromagnetic layer and a non-magnetic layer, or a composite structure consisting of an antiferromagnetic layer, a ferromagnetic layer, and a non-magnetic layer. In the latter composite structure, the magnetization direction of the reference layer 30 is firmly maintained by the antiferromagnetic layer. Therefore, the magnetization of the reference layer 30 is less susceptible to external influences. When the magnetization of the reference layer 30 is oriented in the Z direction (setting the magnetization of the reference layer 30 as a perpendicular magnetization film), it is preferable to also include, for example, a Co / Ni multilayer film or a Co / Pt multilayer film.

[0081] The first magnetization fixing layer 50 and the second magnetization fixing layer 60 are connected to the domain wall moving layer 10. The first magnetization fixing layer 50 and the second magnetization fixing layer 60 are located on the domain wall moving layer 10. The first magnetization fixing layer 50 and the second magnetization fixing layer 60 are separated in the x-direction. The first magnetization fixing layer 50 fixes the magnetization of the first region A1. The second magnetization fixing layer 60 fixes the magnetization of the second region A2.

[0082] The first magnetization fixing layer 50 and the second magnetization fixing layer 60 are, for example, ferromagnetic materials. The first magnetization fixing layer 50 and the second magnetization fixing layer 60 can, for example, be made of the same material as the reference layer 30. Furthermore, the first magnetization fixing layer 50 and the second magnetization fixing layer 60 are not limited to ferromagnetic materials. When the first magnetization fixing layer 50 and the second magnetization fixing layer 60 are not ferromagnetic materials, the movement of the domain wall DW is restricted by drastically changing the current density flowing through the domain wall moving layer 10 in the region overlapping with the first magnetization fixing layer 50 or the second magnetization fixing layer 60, thereby fixing the magnetization of the first region A1 and the second region A2.

[0083] In addition, such as Figure 4 As shown, for example, the width in the y-direction of each of the first magnetization fixing layer 50 and the second magnetization fixing layer 60 is wider than the width in the y-direction of the domain wall moving layer 10. By extending the boundary between the first magnetization fixing layer 50 or the second magnetization fixing layer 60 and the domain wall moving layer 10 along the y-direction of the domain wall moving layer 10, the y-direction magnetic property distribution within the domain wall moving layer 10 becomes uniform. When the y-direction magnetic property distribution within the domain wall moving layer 10 becomes uniform, the tilting of the domain wall DW relative to the y-direction can be suppressed.

[0084] The shapes of the first magnetization fixing layer 50 and the second magnetization fixing layer 60 when viewed from the z-direction are, for example, rectangular. The shapes of the first magnetization fixing layer 50 and the second magnetization fixing layer 60 when viewed from the z-direction can also be, for example, circular, elliptical, oblong, etc.

[0085] The magnetization direction of each layer of the domain wall moving element 100 can be confirmed, for example, by measuring the magnetization curve. The magnetization curve can be measured, for example, using MOKE (Magneto Optical Kerr Effect). MOKE measurement is a measurement method that utilizes the magneto-optical effect (magneto-Kerr effect), which is generated by incident linearly polarized light onto the object being measured, causing a rotation in the direction of its polarization.

[0086] Next, the manufacturing method of the domain wall moving element 100 will be described. The domain wall moving element 100 is formed by a layer stacking process and a processing process of machining a portion of each layer into a predetermined shape. The layer stacking can be performed using sputtering, chemical vapor deposition (CVD), electron beam evaporation (EB evaporation), atomic laser deposition, etc. The machining of each layer can be performed using photolithography and etching (e.g., Ar etching).

[0087] First, a reference layer, a non-magnetic layer, a stack, and a magnetization fixing layer are sequentially stacked on the electrode E and the insulating layer In. The stack is stacked alternately in the order of ferromagnetic layers and intercalation layers, starting from the side closest to the electrode E. Next, unwanted portions of these layers in the x and y directions are removed, for example, by photolithography and etching. After removing the unwanted portions, each layer is processed into a predetermined shape: the reference layer becomes reference layer 30, the non-magnetic layer becomes non-magnetic layer 20, and the stack becomes magnetic domain wall moving layer 10. Next, unwanted portions of the magnetization fixing layer are removed, except for the two portions in the magnetization fixing layer that overlap with the ends of the magnetic domain wall moving layer 10. Through this process, the magnetization fixing layers become the first magnetization fixing layer 50 and the second magnetization fixing layer 60.

[0088] Next, an insulating layer In is stacked on top of the domain wall moving layer 10, the first magnetization fixing layer 50, and the second magnetization fixing layer 60. Then, a cavity is formed at the position where the insulating layer In overlaps with the first magnetization fixing layer 50 and the second magnetization fixing layer 60. By filling the cavity with a conductor, a first conductive layer 71 and a second conductive layer 72 are obtained. Through the above sequence, the domain wall moving element 100 is obtained.

[0089] The domain wall moving element 100 of the first embodiment has multiple ferromagnetic layers 11 containing Co and Fe, sandwiched between an insert layer 12. The magnetization of the ferromagnetic layers 11 exhibits strong perpendicular magnetic anisotropy due to the effect at the interface with the insert layer 12 (interface perpendicular magnetic anisotropy) and the magnetic coupling between the ferromagnetic layers 11 sandwiching the insert layer 12. Therefore, the domain wall moving element 100 exhibits a high MR ratio and excellent controllability of the domain wall DW.

[0090] In contrast, for example, when the insertion layer 12 is removed from the domain wall moving layer 10, the thickness of the ferromagnetic layer 11 increases, and the ferromagnetic layer 11 does not exhibit sufficient perpendicular magnetic anisotropy. When the thickness of the domain wall moving layer 10 (i.e., the single-layer ferromagnetic layer 11) is reduced to maintain perpendicular magnetic anisotropy, the resistance of the domain wall moving layer 10 increases. As a result, a portion of the current flowing along the domain wall moving layer 10 in the x-direction leaks to the reference layer 30 side via the nonmagnetic layer 20, reducing the controllability of the domain wall DW.

[0091] Furthermore, the reference layer 30 of the domain wall moving element 100 is located closer to the substrate Sub than the domain wall moving layer 10. The further the laminated film is from the substrate, the lower its flatness, and the lower the magnetization stability of the magnetic film formed on the laminated film. The reference layer 30 serves as a reference layer for magnetoresistance changes, and by improving the magnetization stability of the reference layer 30, the MR ratio of the domain wall moving element 100 can be improved.

[0092] Furthermore, the domain wall moving element 100 is fabricated starting from the substrate Sub. The insertion layer 12, made of a different material than the ferromagnetic layer 11, functions as an etching stop during manufacturing, preventing damage to the ferromagnetic layer 11. As a result, the MR ratio of the domain wall moving layer 10 is prevented from decreasing due to etching damage. In addition, when the domain wall moving element 100 is heat-treated, the insertion layer 12 prevents element diffusion and also prevents a decrease in the MR ratio of the domain wall moving element 100.

[0093] "Second Implementation Method"

[0094] Figure 5 This is a cross-sectional view obtained by cutting the domain wall moving element 101 of the second embodiment with an xz plane passing through the center of the domain wall moving layer 10 in the y direction. The structures of the first magnetization fixing layer 55 and the second magnetization fixing layer 65 of the domain wall moving element 101 of the second embodiment are different from those of the domain wall moving element 100 of the first embodiment. In the second embodiment, the same symbols are used for structures that are the same as those in the first embodiment, and the description is omitted.

[0095] The first magnetization fixing layer 55 has a magnetic coupling layer 51 and a ferromagnetic layer 52. The magnetic coupling layer 51 and the ferromagnetic layer 52 are stacked alternately. The second magnetization fixing layer 65 has a magnetic coupling layer 61 and a ferromagnetic layer 62. The magnetic coupling layer 61 and the ferromagnetic layer 62 are stacked alternately.

[0096] Ferromagnetic layers 52 and 62 can be made of the same material as reference layer 30. Magnetic coupling layers 51 and 61 are non-magnetic layers. For example, magnetic coupling layers 51 and 61 are made of Ru, Ir, or Rh. Adjacent ferromagnetic layers 52 and 62 are antiferromagnetically coupled to each other.

[0097] The first magnetization fixing layer 55 and the second magnetization fixing layer 65 have different thicknesses. For example, the first magnetization fixing layer 55 and the second magnetization fixing layer 65 have different thicknesses due to the different number of layers they contain. For example, the number of ferromagnetic layers 52 contained in the first magnetization fixing layer 55 is different from the number of ferromagnetic layers 62 contained in the second magnetization fixing layer 65. For example, the first magnetization fixing layer 55 contains two ferromagnetic layers 52, while the second magnetization fixing layer 65 contains one ferromagnetic layer 62.

[0098] The domain wall moving element 101 of the second embodiment can achieve the same effect as the domain wall moving element 100.

[0099] Furthermore, the domain wall moving element 101 of the second embodiment can easily reverse the magnetization orientations of the first region A1 and the second region A2 by applying an external magnetic field in only one direction. The first magnetization fixing layer 55 and the second magnetization fixing layer 65 have different thicknesses and different saturation magnetizations. By utilizing this difference in saturation magnetization, the magnetization orientations of the first magnetization fixing layer 55 and the second magnetization fixing layer 65 can be reversed, thus making the magnetization orientations of the first region A1 and the second region A2 opposite.

[0100] "Third Implementation Method"

[0101] Figure 6 This is a cross-sectional view obtained by cutting the domain wall moving element 102 of the third embodiment with an xz plane passing through the center of the domain wall moving layer 10 in the y direction. The structures of the first magnetization fixing layer 56 and the second magnetization fixing layer 66 of the domain wall moving element 102 of the third embodiment are different from those of the domain wall moving element 101 of the second embodiment. In the third embodiment, the same symbols are used for structures that are the same as those in the second embodiment, and the description is omitted.

[0102] The stacking order of the magnetic coupling layer 51 and the ferromagnetic layer 52 in the first magnetization fixing layer 56 is different from that in the first magnetization fixing layer 55 of the second embodiment. Similarly, the stacking order of the magnetic coupling layer 61 and the ferromagnetic layer 62 in the second magnetization fixing layer 66 is different from that in the second magnetization fixing layer 65 of the second embodiment. In the first magnetization fixing layer 56, the ferromagnetic layer 52 closest to the substrate Sub side is directly connected to the ferromagnetic layer 11 of the domain wall moving layer 10. Similarly, in the second magnetization fixing layer 66, the ferromagnetic layer 62 closest to the substrate Sub side is directly connected to the ferromagnetic layer 11 of the domain wall moving layer 10.

[0103] The domain wall moving element 102 of the third embodiment can achieve the same effect as the domain wall moving element 101. Furthermore, by directly connecting the ferromagnetic layer 11 of the domain wall moving layer 10 with the ferromagnetic layers 52 and 62 of the first magnetization fixing layer 56 and the second magnetization fixing layer 66, the magnetic connection between the domain wall moving layer 10 and the first magnetization fixing layer 56 and the second magnetization fixing layer 66 is enhanced. As a result, the magnetization of the first region A1 and the second region A2 is firmly fixed, preventing the domain wall DW from intruding into the first region A1 or the second region A2.

[0104] "Fourth Implementation Method"

[0105] Figure 7This is a cross-sectional view obtained by cutting the domain wall moving element 103 of the fourth embodiment with an xz plane passing through the center of the domain wall moving layer 13 in the y direction. The structure of the domain wall moving layer 13 of the domain wall moving element 103 of the fourth embodiment is different from that of the domain wall moving element 102 of the third embodiment. In the fourth embodiment, the same symbols are used for structures that are the same as those in the third embodiment, and the description is omitted.

[0106] The domain wall moving layer 13 has a ferromagnetic layer 11 and an insertion layer 12. The ferromagnetic layer 11 and the insertion layer 12 are stacked alternately. The first ferromagnetic layer 11A, which is closest to the nonmagnetic layer 20 among the ferromagnetic layers 11 contained in the domain wall moving layer 13, is thicker than the other ferromagnetic layers 11 contained in the domain wall moving layer 13.

[0107] The domain wall moving element 103 of the fourth embodiment can achieve the same effect as the domain wall moving element 102.

[0108] As described above, since the domain wall moving element 103 is processed from top to bottom, the closer it is to the substrate Sub, the less likely it is to be damaged. By increasing the thickness of the first ferromagnetic layer 11A on the side closest to the substrate Sub, the controllability of the domain wall DW of the domain wall moving element 103 can be improved. In addition, since the insertion layer 12 also functions as an etching stop, by increasing the number of insertion layers 12 above the domain wall moving layer 13, processing damage to the domain wall moving element 103 can be further suppressed.

[0109] "Fifth Implementation Method"

[0110] Figure 8 This is a cross-sectional view obtained by cutting the domain wall moving element 104 of the fifth embodiment with an xz plane passing through the center of the domain wall moving layer 10 in the y direction. The structures of the first magnetization fixing layer 57 and the second magnetization fixing layer 67 of the domain wall moving element 104 of the fifth embodiment are different from those of the domain wall moving element 100 of the first embodiment. In the fifth embodiment, the same symbols are used for structures that are the same as those in the first embodiment, and the description is omitted.

[0111] A portion of the first magnetization fixing layer 57 is inserted into the domain wall moving layer 10. The lower surface 57b of the first magnetization fixing layer 57 is located below the upper surface 10a of the third region A3 of the domain wall moving layer 10. The first magnetization fixing layer 57 is obtained by stacking an insulating layer In on the domain wall moving layer 10, forming a groove on the insulating layer In, and alternately stacking a ferromagnetic layer 53 and a magnetic coupling layer 54 in the groove. The first magnetization fixing layer 57 alternately has a ferromagnetic layer 53 and a magnetic coupling layer 54.

[0112] A portion of the second magnetization fixing layer 67 is inserted into the domain wall moving layer 10. The lower surface 67b of the second magnetization fixing layer 67 is located below the upper surface 10a of the third region A3 of the domain wall moving layer 10. The second magnetization fixing layer 67 is obtained by stacking an insulating layer In on the domain wall moving layer 10, forming a groove in the insulating layer In, and alternately stacking a ferromagnetic layer 63 and a magnetic coupling layer 64 in the groove. The second magnetization fixing layer 67 alternately has a ferromagnetic layer 63 and a magnetic coupling layer 64.

[0113] The upper surfaces 57a of the first magnetization fixing layer 57 and the upper surface 67a of the second magnetization fixing layer 67 are recessed in the z-direction to conform to the shape of the groove. The first conductive layer 73 is fitted into the recess of the upper surface 57a. In addition, the second conductive layer 74 is fitted into the recess of the upper surface 67a.

[0114] Ferromagnetic layers 53 and 63 are made of the same material as ferromagnetic layers 52 and 62. Magnetic coupling layers 54 and 64 are made of the same material as magnetic coupling layers 51 and 61.

[0115] The domain wall moving element 104 of the fifth embodiment can achieve the same effect as the domain wall moving element 100.

[0116] Furthermore, in the domain wall moving element 104 of the fifth embodiment, a portion of the first magnetization fixing layer 57 and the second magnetization fixing layer 67 penetrates relative to the domain wall moving layer 10. Therefore, the magnetic connection between the domain wall moving layer 10 and the first magnetization fixing layer 57 and the second magnetization fixing layer 67 is strong, and magnetization is firmly fixed.

[0117] "Sixth Implementation Method"

[0118] Figure 9 This is a cross-sectional view obtained by cutting the domain wall moving element 105 of the sixth embodiment with an xz plane passing through the center of the domain wall moving layer 10 in the y direction. The domain wall moving element 105 of the sixth embodiment differs from the domain wall moving element 100 of the first embodiment in that it also includes a perpendicular magnetic induction layer 80. In the sixth embodiment, the same reference numerals are used for structures that are the same as those in the first embodiment, and descriptions are omitted.

[0119] A vertical magnetic induction layer 80 is located on the domain wall moving layer 10. For example, the vertical magnetic induction layer 80 is located on the third region A3 of the domain wall moving layer 10. The vertical magnetic induction layer 80 can enhance the vertical magnetic anisotropy of the ferromagnetic layer 11 of the domain wall moving layer 10. The vertical magnetic induction layer 80 may contain, for example, any one selected from MgO, Mg-Al-O, Mg, W, Mo, Ta, Pd, and Pt.

[0120] The domain wall moving element 105 of the sixth embodiment can achieve the same effect as the domain wall moving element 100. In addition, through the vertical magnetic induction layer 80, the vertical magnetic anisotropy of the ferromagnetic layer 11 is increased, and the stability of the domain wall moving element 105 relative to external disturbances is further increased.

[0121] in addition, Figure 10 This is a cross-sectional view of a modified example of the magnetic domain wall moving element according to the sixth embodiment. Figure 10 The domain wall moving element 105A shown extends from the vertical magnetic induction layer 81 between the first magnetization fixing layer 50 and the domain wall moving layer 10, and between the second magnetization fixing layer 60 and the domain wall moving layer 10. Figure 9 The magnetic domain wall moving element 105 shown is different.

[0122] The vertical magnetic induction layer 81 is located at least one of the following: between the first magnetization fixing layer 50 and the domain wall moving layer 10, and between the second magnetization fixing layer 60 and the domain wall moving layer 10. When the vertical magnetic induction layer 81 is located between the first magnetization fixing layer 50 or the second magnetization fixing layer 60 and the domain wall moving layer 10, the magnetization stability of the first region A1 and the second region A2 increases, and domain wall drift (DW) to the first region A1 and the second region A2 can be suppressed. The thickness of the portion of the vertical magnetic induction layer 81 inserted between the first magnetization fixing layer 50 and the domain wall moving layer 10 or between the second magnetization fixing layer 60 and the domain wall moving layer 10 is preferably thicker than the thickness of the inserted layer 12, within a range that can maintain ferromagnetic coupling between the domain wall moving layer 10 and the first magnetization fixing layer 50 or between the domain wall moving layer 10 and the second magnetization fixing layer 60. Alternatively, the thickness of the vertical magnetic induction layer 81 other than the portion inserted between them may be thinner than the portion inserted between them.

[0123] "Seventh Implementation Method"

[0124] Figure 11 This is a cross-sectional view obtained by cutting the domain wall moving element 106 of the seventh embodiment with an xz plane passing through the center of the domain wall moving layer 14 in the y direction. The structure of the domain wall moving layer 14 of the domain wall moving element 106 of the seventh embodiment is different from that of the domain wall moving element 102 of the third embodiment. In the seventh embodiment, the same reference numerals are used for structures that are the same as those in the third embodiment, and descriptions are omitted.

[0125] The domain wall moving layer 14 has a ferromagnetic layer 11 and an insertion layer 12. The ferromagnetic layer 11 and the insertion layer 12 are stacked alternately. The second insertion layer 12B, which is furthest from the non-magnetic layer 20 among the insertion layers 12 included in the domain wall moving layer 13, is thicker than the other insertion layers 12 included in the domain wall moving layer 13.

[0126] The domain wall moving element 106 of the seventh embodiment can achieve the same effect as the domain wall moving element 102.

[0127] As described above, since the domain wall moving element 106 is processed from top to bottom, the closer it is to the substrate Sub, the less likely it is to be damaged. By increasing the thickness of the insertion layer 12 located away from the substrate Sub, processing damage to the domain wall moving element 106 (especially damage to the ferromagnetic layer 11, which has a significant impact on the MR ratio) can be further suppressed.

[0128] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to these embodiments. For example, the feature structures of various embodiments can be combined, and some modifications can be made without changing the spirit of the invention.

[0129] Explanation of symbols

[0130] 10, 13, 14… Domain wall moving layers, 10a, 57a, 67a… Upper surfaces, 11, 52, 53, 62, 63… Ferromagnetic layers, 11A… First ferromagnetic layer, 12… Insertion layer, 12A… First insertion layer, 20… Non-magnetic layer, 30… Reference layer, 40… Magnetoresistive effect element, 50, 55, 56, 57… First magnetization fixing layer, 51, 54, 61, 64… Magnetic coupling layers, 57b, 67b… The following layers are defined as follows: lower surface, 60, 65, 66, 67… second magnetization fixing layer, 71, 73… first conductive layer, 72, 74… second conductive layer, 80, 81… vertical magnetic induction layer, 100, 101, 102, 103, 104, 105… magnetic domain wall moving element, 200… magnetic array, A1… first region, A2… second region, A3… third region, A3a… first magnetic region, A3b… second magnetic region, In… insulating layer.

Claims

1. A magnetic domain wall moving element, wherein, have: A magnetoresistive element, comprising, sequentially from the side closest to the substrate, a reference layer, a non-magnetic layer, and a domain wall moving layer; and The first magnetization fixing layer and the second magnetization fixing layer are respectively in contact with the magnetic domain wall moving layer, and are separated from each other. The domain wall moving layer comprises a ferromagnetic layer, and the ferromagnetic layer comprises multiple insertion layers. The ferromagnetic layer contains Co and Fe and exhibits perpendicular magnetic anisotropy. The inserted layer comprises any one selected from MgO, Mg-Al-O, Mg, W, Mo, Ta, Pd, and Pt. The insertion layer has multiple insertion regions dispersed in an island-like pattern. During writing, the write current flows along the magnetic domain wall moving layer between the first magnetized fixing layer and the second magnetized fixing layer. The first insert layer, which is closest to the non-magnetic layer, comprises any one selected from W, Mo, Ta, Pd, and Pt. Any of the insert layers other than the first insert layer contains MgO or Mg-Al-O.

2. The domain wall moving element according to claim 1, wherein, The first magnetization fixing layer and the second magnetization fixing layer have different thicknesses.

3. The domain wall moving element according to claim 1 or 2, wherein, The first magnetization fixing layer and the second magnetization fixing layer each have alternately stacked magnetic coupling layers and ferromagnetic layers. The number of ferromagnetic layers contained in the first magnetization fixing layer is different from the number of ferromagnetic layers contained in the second magnetization fixing layer.

4. The domain wall moving element according to any one of claims 1 to 3, wherein, The first ferromagnetic layer, which is closest to the non-magnetic layer among the ferromagnetic layers contained in the domain wall moving layer, is thicker than the other ferromagnetic layers contained in the domain wall moving layer.

5. The domain wall moving element according to any one of claims 1 to 4, wherein, The insertion layer furthest from the non-magnetic layer among the insertion layers included in the magnetic domain wall moving layer is thicker than the other insertion layers included in the magnetic domain wall moving layer.

6. The domain wall moving element according to any one of claims 1 to 5, wherein, The lower surfaces of the first magnetization fixing layer and the second magnetization fixing layer are located below the upper surface of the magnetic domain wall moving layer.

7. The domain wall moving element according to any one of claims 1 to 6, wherein, It also has a vertical magnetic induction layer. The vertical magnetic induction layer is located on the magnetic domain wall moving layer.

8. The domain wall moving element according to claim 7, wherein, The vertical magnetic induction layer comprises any one selected from MgO, Mg-Al-O, Mg, W, Mo, Ta, Pd, and Pt.

9. The domain wall moving element according to claim 7 or 8, wherein, The vertical magnetic induction layer is located at least between the first magnetization fixed layer and the magnetic domain wall moving layer, and between the second magnetization fixed layer and the magnetic domain wall moving layer.

10. The domain wall moving element according to any one of claims 1 to 9, wherein, It also has a first conductive layer connected to the first magnetization fixing layer and a second conductive layer connected to the second magnetization fixing layer. The first conductive layer is fitted into a recess formed on the upper surface of the first conductive layer.

11. A magnetic array, wherein, It comprises a plurality of magnetic domain wall moving elements as described in any one of claims 1 to 10.

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