Electrically-controlled vertical magnetic moment overturning method and device, magnetic random access memory and electronic equipment

Abstract

The invention discloses an electrically-controlled vertical magnetic moment flipping method, which is characterized in that the generation of out-of-plane spin polarization current of a spin electronic device is realized by utilizing the low symmetry of a high-index crystal face of a spin source layer, and the vertical magnetic moment of a ferromagnetic layer is flipped in a spin source layer / vertical ferromagnetic layer structure. The low symmetry means that only one single-rotation symmetry axis and one mirror symmetry exist, or only one single-rotation symmetry exists. The spin source layer is of a double-layer composite structure formed by a metal material with strong spin orbit coupling or an orbit Hall layer with a metal material with a strong orbit Hall effect and a spin orbit coupling layer serving as a spin conversion layer. The spin-orbit torque device is simple in structure, practical and easy to prepare, is used for a random access memory, and can be used for high-efficiency electric regulation and control of vertical magnetization overturning under the zero magnetic field.

Description

Technical Field

[0001] This disclosure belongs to the field of spintronic device technology, and specifically relates to an electrically controlled vertical magnetic moment reversal method, device, magnetic random access memory, and electronic device. Background Technology

[0002] The spin-orbit torque (SOT) effect provides a revolutionary all-electric magnetic moment manipulation mechanism, creating conditions for the development of low-power, non-volatile advanced spintronic devices. Taking SOT magnetic random access memory (MRAM) as an example, its purely electrical read / write operations, power-off data retention, ultra-fast speed, high storage density, strong stability, and excellent process adaptability significantly surpass traditional magnetically driven and spin-transfer torque (STT) type MRAMs. The basic structure of a classic spin-orbit torque device is a spin source layer / vertical ferromagnetic layer; the charge flow introduced into the device occurs only in the vertical charge flow... y The direction generates spin polarization, which cannot achieve a deterministic reversal of the vertical magnetic moment. Other techniques are usually needed to break the in-plane symmetry to achieve a deterministic reversal of the vertical magnetic moment. When a spin-orbit torque device can generate an out-of-plane spin-polarized current, a deterministic reversal of the vertical magnetic moment can be achieved.

[0003] Due to the multifunctional operation of existing spin-orbit torque devices, external magnetic fields are generally required for assistance, or the introduction of in-plane equivalent magnetic fields and asymmetric designs are needed to break symmetry in order to achieve vertical magnetic moment reversal. These methods inevitably lead to problems such as cumbersome system design, increased energy consumption, and limited integration, stemming from the limitation that classic spin-orbit torque devices cannot generate out-of-plane spin polarization currents. Therefore, realizing a simple, practical, and easily fabricated spin-orbit torque device capable of high-efficiency electrically controlled vertical magnetization reversal under zero magnetic field conditions is a pressing problem to be solved. Summary of the Invention

[0004] To address the problems in the prior art, this disclosure proposes an electrically manipulated vertical magnetic moment reversal method. This method utilizes the low symmetry of the high-index crystal plane of the spin source layer to generate out-of-plane spin polarization current in a spintronic device, and reverses the vertical magnetic moment of the ferromagnetic layer in the spin source layer / vertical ferromagnetic layer structure SA.

[0005] One aspect of this disclosure is a method for generating out-of-plane spin-polarized current to electrically manipulate the reversal of the perpendicular magnetic moment. This method involves sequentially growing a high-index oriented spin source layer and a ferromagnetic layer on a substrate. The high-index crystal orientation of the spin source layer is controlled by the lattice orientation of the substrate, achieving low symmetry in the growth orientation crystal planes of the spin source layer. This method utilizes the low symmetry of the high-index crystal planes of the spin source layer to generate an out-of-plane spin-polarized current and reverse the perpendicular magnetic moment of a magnetic material, such as a ferromagnetic layer. The low symmetry described here refers to either the existence of only one rotational symmetry axis and a mirror symmetry, or the existence of only one rotational symmetry.

[0006] The spin source layer is composed of Pt, Cu, Au, Ir, Pd, Rh, Al, and other elements with a high-exponential orientation. γ Metals or alloys of any proportion exhibiting strong spin-orbit coupling or strong orbital Hall effect, such as Fe, Ce, Th, Ge, W, Ta, Mo, Mn, Cr, V, Nb, V, α-Fe, Ti, Sc, Cd, Tc, Zr, Hf, Ru, Zn, Gd, Tb, Tm, Ho, Dy, Er, and Lu. The spin source layer is not limited to a single-layer configuration. When using metals with strong orbital Hall effect (including but not limited to Ti, Cr, Mo, and V), a spin-orbit coupling layer (including but not limited to Pt, Ta, and W) is required as a spin-switching layer. In this case, the spin source layer is a two-layer composite structure consisting of an orbital Hall layer and a spin-switching layer.

[0007] The substrate has a surface atomic arrangement structure that matches the high-index crystal plane of the high-index spin source layer.

[0008] The ferromagnetic layer is a ferromagnetic heterostructure with a perpendicular magnetic moment. The ferromagnetic heterostructure with a perpendicular magnetic moment includes, but is not limited to, structures such as CoFeB / MgO, Co / Pt, Co / Pd, Co / W, Co / Ta, Fe / W, L10-FePt, CoPt, TbFeCo, and GdFeCo.

[0009] One aspect of this disclosure is an electrically controlled method for reversing the vertical magnetic moment. This method utilizes the low symmetry of a high-index crystal plane of a spin source layer to generate an out-of-plane spin polarization current, thereby reversing the vertical magnetic moment without the assistance of an external magnetic field. The low symmetry refers to the existence of only one rotational symmetry axis plus one mirror symmetry, or only one rotational symmetry.

[0010] The spin source layer is Pt, Cu, Au, Ir, Pd, Rh, Al. γMetals or alloys exhibiting strong spin-orbit coupling or strong orbital Hall effect, such as Fe, Ce, Th, Ge, W, Ta, Mo, Mn, Cr, V, Nb, V, α-Fe, Ti, Sc, Cd, Tc, Zr, Hf, Ru, Zn, Gd, Tb, Tm, Ho, Dy, Er, and Lu, are used. The substrate has a surface atomic arrangement structure matching the high-index crystal planes of the spin source layer. The ferromagnetic layer forms a ferromagnetic heterostructure with a perpendicular magnetic moment.

[0011] One aspect of this disclosure is a method for fabricating an electrically controlled vertical magnetic moment reversal device, in which a high-index oriented spin source layer and a ferromagnetic layer are sequentially grown on a substrate. The high-index crystal orientation of the spin source layer is controlled by the lattice orientation of the substrate, thereby achieving low symmetry of the high-index oriented crystal planes of the spin source layer.

[0012] In one aspect of this disclosure, there is an electrically controlled vertical magnetic moment reversal device, the device having a substrate and a high-index spin source layer and a ferromagnetic layer grown sequentially on the substrate, wherein the high-index crystal orientation of the spin source layer is controlled by the lattice orientation of the substrate to achieve low symmetry of the high-index growth orientation crystal plane of the spin source layer.

[0013] Pinning layers are grown on the ferromagnetic layer.

[0014] In one aspect of this disclosure, a magnetic random access memory includes a plurality of memory cells, each memory cell including the aforementioned electrically controlled vertical magnetic moment reversal device.

[0015] One aspect of this disclosure is an electronic device that includes a magnetic random access memory as described above.

[0016] This disclosure presents a simple, practical, and easily scalable spin torque device for next-generation random access memory (RAM) with high-efficiency electrically controllable vertical magnetization reversal under zero magnetic field. The proposed device structure is not only advanced in principle but also simple in design and highly compatible with mainstream semiconductor processes. It provides a novel underlying technology solution for developing next-generation high-speed, low-power, high-density magnetic RAM, demonstrating significant potential for practical application and large-scale production. It will play a crucial role in applications with extremely high requirements for storage performance and energy efficiency, such as artificial intelligence, big data centers, and the Internet of Things. Attached Figure Description

[0017] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of the invention are illustrated in the drawings by way of example and not limitation, wherein: Figure 1 According to one embodiment of the present disclosure, the C-plane of the high-index (210) surface of the spin source Pt 1v Schematic diagram of symmetry.

[0018] Figure 2 A schematic diagram of the C1 symmetry of the high-index (321) plane of a spin source Pt according to one embodiment of the present disclosure.

[0019] Figure 3 A schematic diagram of a method for fabricating a vertical magnetic moment reversing device according to one embodiment of the present disclosure.

[0020] Figure 4 A schematic diagram of a stacked structure of a vertical magnetic moment reversing device according to one embodiment of the present disclosure.

[0021] Figure 5 A schematic diagram of the current-driven reversal curve of a Pt(210) / Ti / CoFeB / MgO / Ta vertical magnetic moment reversal device without external field assistance, according to one embodiment of the present disclosure.

[0022] Figure 6 According to one of the embodiments of this disclosure, Pt(110), Pt(210), Pt(310) and Pt(410) based devices and in-plane spin Hall conductance of other materials σ s,y Out-of-plane spin Hall conductance σ s,z A comparison diagram.

[0023] Figure 7 A schematic diagram of a magnetic tunnel junction device according to one embodiment of the present disclosure. Detailed Implementation

[0024] According to one or more embodiments, in order to solve the problems in the prior art, this disclosure provides a method and device for generating out-of-plane spin polarization current and realizing current-controlled reversal of the vertical magnetic moment without the assistance of an external magnetic field. Specifically, the device includes a high-index oriented spin source layer for generating out-of-plane spin polarization current and a ferromagnetic heterojunction with a vertical magnetic moment. Device fabrication includes sequentially fabricating a substrate, a high-index oriented spin source layer, and a vertical ferromagnetic heterojunction. The high-index oriented spin source layer is grown on the substrate using epitaxial technology. The crystal orientation of the epitaxial spin source layer is controlled by matching the atomic arrangement of a specific crystal plane of the substrate with the high-index crystal plane of the spin source layer, thereby achieving low symmetry of the epitaxial growth orientation crystal plane of the spin source layer, i.e., crystal symmetry design. The low symmetry of the epitaxial orientation crystal plane of the high-index spin source layer includes two types of symmetry: 1. There exists only one axis of rotational symmetry and one mirror symmetry (C). 1v Symmetry, equivalent to C s symmetry); 2. There is only one one-dimensional rotational symmetry (C1 symmetry, i.e., no symmetry).

[0025] The single rotational symmetry here means that there is no symmetry at all; it only coincides with itself after rotating 360°. Either of the two symmetries satisfies the condition for generating out-of-plane spin-polarized current.

[0026] The spin source layer can be made of Pt, Cu, Au, Ir, Pd, Rh, Al, etc. γ High-index crystal planes of metals or alloys of any elemental proportions, including Fe, Ce, Th, Ge, W, Ta, Mo, Mn, Cr, V, Nb, V, α-Fe, Ti, Sc, Cd, Tc, Zr, Hf, Ru, Zn, Gd, Tb, Tm, Ho, Dy, Er, and Lu, which possess strong spin-orbit coupling or strong orbital Hall effect, are given below. The high-index crystal planes of face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal (HCP) structures are also listed. 1v Examples of symmetry and / or C1 symmetry. Here, FCC stands for Face Centered Cubic; BCC stands for Body Centered Cubic; HCP stands for Hexagonal Close Packed; C1v represents a symmetry with a vertical mirror plane; C1 represents a symmetry with no symmetry operations, only identity operations. FCC, BCC, and HCP are all crystal structures.

[0027] Among them, for the C of the high index crystal plane 1v The face-centered cubic (FCC) structure, representing one embodiment of symmetry and / or C1 symmetry, relates to metallic and alloy materials, including Pt, Cu, Au, Ir, Pd, Rh, Al, and other metals. γ -Fe, Ce, Th, Ge, and alloys of any elements and proportions having a face-centered cubic structure.

[0028] High-index crystal planes of face-centered cubic metallic materials have C 1v Examples of symmetry include, but are not limited to, (210), (310), (410), (510), (610), (710), ××××××, (211), (311), (411), ×××××× (221), (331), (441), ×××××× etc. hkl Crystal planes and their equivalent crystal plane families: {210}, {310}, {410}, {510}, {610}, {710}, ××××××, {211}, {311}, {411}, ××××××, {221}, {331}, {441} ××××××{ hk l} etc. Here h, k, lYou can take any number, just ( hkl Crystal planes satisfy C 1v Symmetry is sufficient. These crystal planes are equivalent to their equivalent crystal plane families. For example, the equivalent crystal planes of the {210} crystal plane family include (210), (201), (102), (120), (012), (021), (20-1), (10-2), (1-20), (01-2), (02-1), (-201), (-102), (-120), (-012), (-021), etc.

[0029] Examples of high-index crystal planes with C1 symmetry in face-centered cubic metallic materials include, but are not limited to, (321), (341), (351), (361), ××××××, (421), (451), (461), ××××××, (521), (561), (571), ××××××, etc. hkl Crystal planes and their equivalent crystal plane families: {321}, {341}, {351}, ××××××, {421}, {451}, {461}, ××××××, {521}, {561}, {571}, ×××××× hk l} etc. Here h, k, l You can take any number, just ( hkl The crystal planes only need to satisfy C1 symmetry. hkl Crystal planes equivalently include their { hkl Equivalent crystal plane family.

[0030] For high index crystal plane C 1v The body-centered cubic (BCC) structure, one of the embodiments of symmetry and / or C1 symmetry, relates to metals and their alloys, including W, Ta, Mo, Mn, Cr, V, Nb, V, α-Fe, and alloys of any elements and proportions having a body-centered cubic structure.

[0031] High-index crystal planes of body-centered cubic metallic materials have C 1v Examples of symmetry include, but are not limited to, (210), (310), (410), (510), (610), (710), ××××××, (211), (311), (411), ×××××× (221), (331), (441), ×××××× etc. hkl Crystal planes and their equivalent crystal plane families: {210}, {310}, {410}, {510}, {610}, {710}, ××××××, {211}, {311}, {411}, ××××××, {221}, {331}, {441} ××××××{ hk l} etc. Hereh, k, l You can take any number, just ( hkl Crystal planes satisfy C 1v Symmetry is sufficient.

[0032] Examples of high-index crystal planes with C1 symmetry in body-centered cubic metallic materials include, but are not limited to, (321), (341), (351), (361), ××××××, (421), (451), (461), ××××××, (521), (561), (571), ××××××, etc. hkl Crystal planes and their equivalent crystal plane families: {321}, {341}, {351}, ××××××, {421}, {451}, {461}, ××××××, {521}, {561}, {571}, ×××××× hk l} etc. Here h, k, l You can take any number, just ( hkl The crystal planes only need to satisfy C1 symmetry. hkl Crystal planes equivalently include their { hkl Equivalent crystal plane family.

[0033] For high index crystal plane C 1v The close-packed hexagonal structure (HCP) of one of the symmetry and / or C1 symmetry embodiments involves metals and their alloys, the body-centered cubic metals including Ti, Sc, Cd, Tc, Zr, Hf, Ru, Zn, Gd, Tb, Tm, Ho, Dy, Er, Lu, and alloys of any elements and proportions having a close-packed hexagonal structure.

[0034] High-index crystal planes of close-packed hexagonal metallic materials have C 1v Examples of symmetry include, but are not limited to, (111), (112), (113), (140), (410), ××××××, etc. hkl Crystal planes and their corresponding equivalent crystal planes. Here... h、 k、l You can take any number, just ( hkl Crystal planes satisfy C 1v Symmetry is sufficient.

[0035] Examples of high-index crystal planes with C1 symmetry in close-packed hexagonal metallic materials include, but are not limited to, (121), (211), (131), (311), ××××××, etc. hkl Crystal planes and their corresponding equivalent crystal planes. Here... h, k, l You can take any number, just ( hkl The crystal planes only need to satisfy C1 symmetry.

[0036] In this embodiment of the disclosure, the substrate is selected as a specific orientation substrate, which has a surface atomic arrangement structure matching the high index crystal plane of the spin source layer, such as {210}, {310}, {410}, {510}, {610}, {710}, etc. of Pt, {211}, {311}, {411}, etc., {221}, {331}, {441}, etc., {321}, {341}, {351}, etc., {421}, {451}, {461}, etc., {521}, {561}, {571}, etc. hk The l} crystal plane orientations adapted to SrTiO3 substrates include {210}, {310}, {410}, {510}, {610}, {710}, ××××××, {211}, {311}, {411}, ××××××, {221}, {331}, {441}, ××××××, {321}, {341}, {351}, ××××××, {421}, {451}, {461}, ××××××, {521}, {561}, {571}, ××××××, etc. hk l} crystal plane orientation. Similarly, BaTiO3, NdGaO3, LaAlO3, LaLuO3, LaScO3, CeScO3, PrScO3, NdScO3, SmScO3, EuScO3, GdScO3, TbScO3, DyScO3, Sr2(GaAl)TaO6, LaGaO3, NdGaO3, SrLaGaO4, SrPrGaO4, (LaSr)(AlTa)O3, (NdSr)(AlTa)O3, NdAlO3, SrLaAlO4, and SrP are perovskite lattice structures. rAlO4, YAlO3, GaNdAlO4, LuAlO3, quasi-cubic lattice {210}, {310}, {410}, {510}, {610}, {710}, etc., {211}, {311}, {411}, etc., {221}, {331}, {441}, etc., {321}, {341}, {351}, etc., {421}, {451}, {461}, etc., {521}, {561}, {571}, etc. hk{110} crystal planes of MgO are compatible with the {211} crystal planes of W, Ta, Mo, Nb, Cr, V, etc. The {210} crystal planes of MgO are compatible with the {411} crystal planes of W, Ta, Mo, Mn, Cr, V, Nb, V, α-Fe, etc. The {211} crystal planes of MgO are compatible with the {210} crystal planes of W, Ta, Mo, Mn, Cr, V, Nb, V, α-Fe, etc. The {311} crystal planes of MgO and other materials are compatible with the {310} crystal planes of W, Ta, Mo, Mn, Cr, V, Nb, V, α-Fe, etc. This also applies to substrates with high-index orientations, including Si, Ge, GaAs, GaN, SiC, InP, and Al2O3.

[0037] High-index oriented spin source layers need to be epitaxially grown on a substrate, which can be achieved through various epitaxial techniques, such as magnetron sputtering, molecular beam epitaxy, and pulsed laser deposition.

[0038] The embodiments disclosed herein provide a device that uses a high-index spin source layer to generate out-of-plane spin polarization current and deterministically flips the vertical magnetic moment. Its device structure consists of only a high-index spin source layer and a vertical magnetic moment ferromagnetic layer, both of which can be fabricated by magnetron sputtering. It features a simple structure, practicality, and ease of large-scale fabrication.

[0039] According to one or more embodiments, based on the physical mechanism of spin-moment reversal and perpendicular magnetization, conventional spin-moment devices, due to the existence of only in-plane spin polarization, require external magnetic field assistance, or the introduction of an in-plane equivalent magnetic field and asymmetric design to break the symmetry in reversing the perpendicular magnetic moment. Therefore, this disclosure proposes a method to generate out-of-plane spin-polarized current using the low-plane symmetry of a high-index spin source layer, to achieve zero-magnetic-field electrically controlled reversal of the perpendicular magnetic moment. When the spin source layer has only one mirror plane and one rotational symmetry in the direction perpendicular to the sample film surface normal, applying current perpendicular to the mirror plane will allow the generation of an out-of-plane spin-polarized current. Furthermore, with only one rotational symmetry, applying current in any direction within the plane perpendicular to the sample film surface will allow the generation of an out-of-plane spin-polarized current.

[0040] Figure 3 The present disclosure illustrates a method for fabricating a vertical magnetic moment reversal device according to an embodiment of the present disclosure, particularly the growth method of a high-index spin source layer Pt(210), the growth steps of which are as follows: (1) Based on the atomic arrangement structure of the Pt (210) crystal plane of the high index spin source layer, a SrTiO3 substrate with (210) orientation is selected.

[0041] (2) Using magnetron sputtering, preferably in the temperature range of 200°C to 800°C, a Pt thin film metal layer is grown.

[0042] (3) A magnetic layer with perpendicular magnetic anisotropy is grown at room temperature. In this embodiment, it is a Ti / CoFeB / MgO / Ta structure, with a CoFeB / MgO heterojunction as the core. The buffer layer Ti and the protective layer Ta are replaceable. This layer serves as a free layer, and pinning layers can be grown on it to form a tunnel junction, such as... Figure 3 As shown.

[0043] Figure 7 This illustration shows a schematic diagram of a magnetic tunnel junction, the basic structural unit of a magnetic random access memory, fabricated using a high-index spin source layer according to an embodiment of this disclosure. Taking a high-index spin source layer Pt(210) as an example, its fabrication process is as follows: (1) Growth of high-index oriented spin source layer - Based on the atomic arrangement structure of the Pt (210) crystal plane of the high-index spin source layer, a (210) oriented SrTiO3 substrate is selected. Using magnetron sputtering, a Pt thin film metal layer is grown as a high-index spin source layer in the preferred temperature range of 200℃ to 800℃.

[0044] (2) Free layer growth - A magnetic layer with perpendicular magnetic anisotropy is grown at room temperature. In this embodiment, the structure is Ti / CoFeB / MgO, with the core being a CoFeB / MgO heterojunction. The buffer layer Ti and the protective layer Ta can be replaced. 2 nm Ti, 1 nm CoFeB, and 1-10 nm MgO are grown sequentially on a high-index Pt thin film at room temperature.

[0045] (3) Pinned layer growth - A pinned layer with the magnetic moment direction fixed in the vertical direction is grown on the free layer. In this embodiment, it is a Co / Pt bilayer film, which is grown at room temperature by magnetron sputtering.

[0046] It should be understood that in the embodiments of the present invention, the term "and / or" is merely a description of the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, the character " / " in this document generally indicates that the preceding and following associated objects have an "or" relationship.

[0047] It is worth noting that although the spirit and principles of this invention have been described with reference to several specific embodiments, it should be understood that this invention is not limited to the disclosed specific embodiments, and the division of aspects does not imply that the features in these aspects cannot be combined; such division is merely for the convenience of description. This invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A method of electrically manipulating a perpendicular magnetic moment flip, the method comprising: The method utilizes the low symmetry of a high-index crystal surface of a spin source layer to generate out-of-plane spin-polarized current of a spintronic device, and to flip the perpendicular magnetic moment of a ferromagnetic layer in a spin source layer / vertical ferromagnetic layer structure.

2. The method of claim 1, wherein, The low symmetry refers to only one one-fold rotational symmetry axis + one mirror symmetry, or only one one-fold rotational symmetry.

3. The method of claim 2, wherein, The spin source layer is composed of a double-layer composite structure of a metal material with strong spin-orbit coupling, or an orbital Hall layer of a metal material with strong orbital Hall effect and a spin-orbit coupling layer as a spin conversion layer.

4. The method of claim 1, wherein, The method grows a high-index orientation spin source layer and a ferromagnetic layer on a substrate in sequence, controls the high-index crystal orientation of the spin source layer through the lattice orientation of the substrate, and realizes the low symmetry of the growth orientation crystal surface of the spin source layer.

5. The method of claim 1, wherein, The ferromagnetic layer has a ferromagnetic heterojunction with a perpendicular magnetic moment, which includes but is not limited to CoFeB / MgO, Co / Pt, Co / Pd, Co / W, Co / Ta, Fe / W, L10-FePt, CoPt, TbFeCo, GdFeCo structure.

6. A method for fabricating an electrically controlled vertical magnetic moment reversal device, characterized in that, The method grows a high-index orientation spin source layer and a ferromagnetic layer on a substrate in sequence, controls the high-index crystal orientation of the spin source layer through the lattice orientation of the substrate, and realizes the low symmetry of the growth orientation crystal surface of the spin source layer.

7. An electrically manipulated perpendicular magnetic moment flipping device, characterized in that, The device structure has a substrate, and a high-index spin source layer and a ferromagnetic layer grown on the substrate in sequence, the high-index crystal orientation of the spin source layer is controlled through the lattice orientation of the substrate to realize the low symmetry of the growth orientation crystal surface of the spin source layer.

8. The electrically manipulated perpendicular magnetic moment flipping device of claim 7, wherein, A pinning layer is grown on the ferromagnetic layer.

9. A magnetic random access memory, comprising: The memory device includes a plurality of memory cells, each memory cell including the device of claim 7 or 8.

10. An electronic device, comprising: The magnetic random access memory includes the device of claim 9.

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