Spin splitting-ferromagnetic coupling materials and their applications

Abstract

The present invention provides a spin-splitting-ferromagnetic coupling material and its application. The spin-splitting-ferromagnetic coupling material including the spin-splitting material and the doping element is obtained by doping the spin-splitting material. The spin-splitting-ferromagnetic coupling material has both energy band spin splitting and ferromagnetism, wherein the energy band spin splitting characteristic lies in the spin-splitting material, and the ferromagnetism characteristic lies in the doping element. The spin-splitting-ferromagnetic coupling material provided by the present invention can realize all-electric spin-orbit torque drive control to eliminate the heterogeneous structure formed by the spin-splitting material and the ferromagnetic material under the traditional spin-orbit torque, thereby simplifying the device structure prepared subsequently and reducing energy loss.

Description

Technical Field

[0001] The invention belongs to the field of spin electronics and relates to a spin splitting-ferromagnetic coupling material and application thereof. Background Art

[0002] With the development of spin electronics, various magnetic devices are widely used in people's daily lives, such as MRAM (Magnetoresistive Random Access Memory), which is a non-volatile magnetic random access memory. It has gone through three generations of development, from the initial magnetic field-driven MRAM to spin transfer torque MRAM (STT-MRAM), and then to spin orbit torque MRAM (SOT-MRAM).

[0003] The magnetic moment reversal force of SOT-MRAM comes from SOT, which is theoretically stronger than the STT force in the previous generation STT-MRAM and has lower theoretical power consumption. However, the heterogeneous structure between the strong spin-orbit coupling (SOC) material in SOT and the adjacent ferromagnetic free layer will produce additional interface scattering at the interface, causing energy loss.

[0004] Therefore, it is necessary to provide a spin splitting-ferromagnetic coupling material and application thereof. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a spin splitting-ferromagnetic coupling material and its application, so as to solve the problem of interface scattering and energy loss generated by the spin splitting-ferromagnetic heterostructure in the prior art.

[0006] To achieve the above-mentioned purpose and other related purposes, the present invention provides a spin splitting-ferromagnetic coupling material, wherein the spin splitting-ferromagnetic coupling material includes a spin splitting material and a doping element, and the spin splitting-ferromagnetic coupling material has both energy band spin splitting and ferromagnetism, wherein the characteristic of energy band spin splitting lies in the spin splitting material, and the characteristic of ferromagnetism lies in the doping element.

[0007] Optionally, the spin-splitting material includes one of BiTeI, COs, CdTe, HgTe, ZnTe, PtN2 and WN2; the doping element includes one or a combination of heavy elements or light elements that provide local asymmetric electrons; the heavy elements include Cr, Mn, Mo, W, V, Fe, Co, Ni, Pd and Sc, and the light elements include H, Li and B.

[0008] Optionally, the spin splitting energy of the spin splitting material is greater than 0.1 eV; the average atomic magnetic moment of the spin splitting-ferromagnetic coupling material is greater than 0.02 μB / atom.

[0009] Optionally, the spin splitting-ferromagnetic coupling material is an all-electrically driven spin splitting-ferromagnetic coupling material, and the magnetic moment of the spin splitting-ferromagnetic coupling material is flipped by current regulation in the absence of an external magnetic field.

[0010] Optionally, a step of assisting with applying an external magnetic field is added.

[0011] The present invention also provides a device structure, wherein the device structure is prepared from the spin splitting-ferromagnetic coupling material.

[0012] The present invention also provides a magnetic tunnel junction, which includes a magnetic free layer, a non-magnetic barrier layer and a magnetic fixed layer arranged from top to bottom, and the magnetic free layer is prepared from the above spin splitting-ferromagnetic coupling material.

[0013] The present invention also provides an MRAM unit, which includes a top electrode, the magnetic tunnel junction and a bottom electrode.

[0014] Optionally, the top electrode is arranged in parallel with the bottom electrode, a read current passes through the magnetic tunnel junction, and a write current passes through the electrode.

[0015] The present invention also provides a magnetic tunnel junction device, which includes the magnetic tunnel junction.

[0016] The present invention also provides an electronic device, wherein the electronic device comprises the magnetic tunnel junction.

[0017] As described above, the spin splitting-ferromagnetic coupling material and its application of the present invention are obtained by doping the spin splitting material to obtain the spin splitting-ferromagnetic coupling material including the spin splitting material and the doping element, and the spin splitting-ferromagnetic coupling material has both energy band spin splitting and ferromagnetism, wherein the characteristic of energy band spin splitting lies in the spin splitting material, and the characteristic of ferromagnetism lies in the doping element. The spin splitting-ferromagnetic coupling material provided by the present invention can realize the all-electrical spin-orbit torque drive control to eliminate the heterogeneous structure formed by the spin splitting material and the ferromagnetic material under the traditional spin-orbit torque, thereby simplifying the device structure prepared subsequently and reducing energy loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown is a schematic diagram of the spin splitting energy band structure of the spin splitting material CdTe in the embodiment.

[0019] Figure 2 The spin splitting-ferromagnetic coupling material W shown in the embodiment 0.17 Cd 0.83 Magnetic moment reversal curve of Te.

[0020] Figure 3 Shown is a schematic structural diagram of a magnetic tunnel junction in an embodiment.

[0021] Figure 4 Shown is a schematic diagram of a read and write path based on a magnetic tunnel junction in an embodiment.

[0022] Figure 5 Shown is a schematic diagram of the definition of spin splitting energy.

[0023] Component number description

[0024] 100 Magnetic Free Layer

[0025] 200 Non-magnetic barrier layer

[0026] 300 Magnetic fixed layer

[0027] 400 Top Electrode

[0028] 500 Bottom electrode

[0029] 600, 700 current DETAILED DESCRIPTION

[0030] Based on the development of spin electronics, simplifying device structure and reducing energy loss have become urgent problems that need to be solved. According to the research of the inventors, if a material is prepared so that the material can have both strong SOC effect and ferromagnetism, then in theory, the SOT effect of the material itself can be used to flip the material's own magnetic moment.

[0031] This embodiment provides a "spin splitting-ferromagnetic" coupling (spin-splitting-ferromagnetic coupling, SSFC) material and its application that generates spin-orbit torque by all-electric drive. The magnetic moment of the material is flipped by the SOT effect of the material itself, and the SOT can be generated by all-electric means. The specific mechanism of action is: in a material with broken spatial symmetry, under the action of the SOC effect, the material produces a spin splitting effect, and after the charge flow passes through the material, a non-equilibrium spin accumulation is generated at the interface, forming a field-like spin orbital torque (field-like spin orbital torque, F-SOT) similar to a magnetic field, which can flip the direction of the magnetic moment of the material itself. Therefore, the spin splitting-ferromagnetic coupling material can eliminate the heterogeneous structure of the SOC material / ferromagnetic material under the existing SOT mechanism, thereby simplifying the device structure and reducing energy loss.

[0032] The spin splitting-ferromagnetic coupling material can be used to prepare magnetic tunnel junctions (MTJs), and the MTJ structure can be prepared by PVD magnetron sputtering, ultraviolet lithography, argon ion etching and other methods. The MTJ structure can also be used in other magnetic devices and electronic devices, such as magnetic random access memories (MRAMs).

[0033] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0034] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0035] For ease of description, spatial relational terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatial relational terms are intended to include other directions of the device in use or operation in addition to the directions depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can be one or more intervening layers. As used herein, "between..." means including the end point values.

[0036] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0037] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0038] The present embodiment provides a spin splitting-ferromagnetic coupling material, which includes a spin splitting material and a doping element. The spin splitting-ferromagnetic coupling material has both energy band spin splitting and ferromagnetism, wherein the characteristic of the energy band spin splitting lies in the spin splitting material, and the characteristic of the ferromagnetism lies in the doping element.

[0039] Specifically, the spin splitting material itself is a non-magnetic material with a spin splitting effect, and the doping element can make the spin splitting-ferromagnetic coupling material have ferromagnetism, wherein the characteristic of energy band spin splitting in the spin splitting-ferromagnetic coupling material comes from the Rashba effect, Dresselhaus effect, Zeeman-like effect, Hidden-Rashba effect, Hidden-Dresselhaus effect or strong spin splitting effect caused by symmetry of the spin splitting material, and the ferromagnetism comes from the element doping of the spin splitting material, so that the spin splitting-ferromagnetic coupling material has the characteristics of mutual coupling of energy band spin splitting and ferromagnetism, so that the magnetic moment of the material can be flipped by electric current.

[0040] As an example, the spin-splitting material includes one of BiTeI, COs, CdTe, HgTe, ZnTe, PtN2 and WN2.

[0041] Specifically, the spin splitting material itself is a non-magnetic material with a spin splitting effect to provide energy band spin splitting performance, wherein the energy band spin splitting characteristics can be derived from the Rashba effect, Dresselhaus effect, Zeeman-like effect, Hidden-Rashba effect, Hidden-Dresselhaus effect or strong spin splitting effect caused by symmetry of the spin splitting material.

[0042] As an example, the doping element may include one or a combination of heavy elements or light elements providing local asymmetric electrons.

[0043] Specifically, since the spin splitting material itself only has a spin splitting effect and is not a magnetic material, when heavy elements or light elements that provide local asymmetric electrons are doped into the spin splitting material, based on the properties of the doped elements, the spin splitting material with the doped elements can be made ferromagnetic with spin splitting and ferromagnetism to form the spin splitting-ferromagnetic coupling material whose magnetic moment can be flipped by electric current.

[0044] The method for forming the spin splitting-ferromagnetic coupling material may be PVD magnetron sputtering, but is not limited thereto.

[0045] As examples, the heavy elements may include Cr, Mn, Mo, W, V, Fe, Co, Ni, Pd and Sc, and the light elements are non-magnetic elements and may include H, Li and B. The selection of doping elements may be flexibly changed according to the specific preparation and is not overly limited here.

[0046] As an example, the spin splitting energy of the spin splitting material is greater than 0.1 eV; the average atomic magnetic moment of the spin splitting-ferromagnetic coupling material is greater than 0.02 μ B / atom.

[0047] Specifically, Figure 5 For Rashba and Dreselhaus types of spin splitting, E0 is the energy difference between the energy extreme point and the energy degenerate point. For Zeeman-like types of spin splitting, E0 is the energy difference between the two splitting energy bands at high symmetry points.

[0048] As an example, the spin splitting-ferromagnetic coupling material is a fully electrically driven spin splitting-ferromagnetic coupling material, so that the spin splitting-ferromagnetic coupling material can flip the magnetic moment of the spin splitting-ferromagnetic coupling material by current regulation in the absence of an external magnetic field, but it is not limited to this. Furthermore, the spin splitting-ferromagnetic coupling material can also be assisted by adding an external magnetic field to further improve the magnetic moment flipping efficiency by applying an external magnetic field, thereby optimizing the performance of the device.

[0049] Specifically, in materials with broken spatial symmetry, under the action of the SOC effect, the material produces a spin splitting effect. After the charge flow passes through the material, non-equilibrium spin accumulation is generated at the interface, forming an F-SOT similar to a magnetic field. This torque can flip the direction of the magnetic moment of the material itself, so that the spin splitting-ferromagnetic coupling material flips the magnetic moment of the material through a purely electrically driven spin-orbit torque, which can eliminate the heterostructure formed by the spin splitting material and the ferromagnetic material under the traditional spin-orbit torque, simplify the device structure, and reduce energy loss.

[0050] This embodiment also provides a device structure, which can be prepared from the spin splitting-ferromagnetic coupling material. For example, the spin splitting-ferromagnetic coupling material can be used to prepare a spin transistor, etc. The type of the device structure is not limited to this.

[0051] like Figure 3 This embodiment also provides a magnetic tunnel junction, which includes a magnetic free layer 100, a non-magnetic barrier layer 200 and a magnetic fixed layer 300 arranged from top to bottom, and the magnetic free layer 100 is prepared by the above-mentioned spin splitting-ferromagnetic coupling material.

[0052] Specifically, the non-magnetic barrier layer 200 may be an oxide layer, an organic material layer or a semiconductor material layer, and the non-magnetic barrier layer 200 may include a combination of one or more doping elements selected from but not limited to Al, Mg, Ti, Zn, Si, C, H, O, Ga, As, In, Mn and P. The material of the magnetic fixed layer 300 is not limited here.

[0053] The magnetic tunnel junction can be prepared by PVD magnetron sputtering, ultraviolet lithography, argon ion etching and other methods, which will not be described in detail here.

[0054] Furthermore, this embodiment also provides an MRAM cell, which includes a top electrode, the magnetic tunnel junction and a bottom electrode.

[0055] As an example, the top electrode is arranged in parallel with the bottom electrode, a read current passes through the magnetic tunnel junction, and a write current passes through the electrodes.

[0056] Furthermore, this embodiment also provides a magnetic tunnel junction device, which includes the magnetic tunnel junction. The magnetic tunnel junction device may include a magnetic read head, etc., and the type of the magnetic tunnel junction device is not limited thereto.

[0057] Furthermore, this embodiment also provides an electronic device, which includes the magnetic tunnel junction. The electronic device may include, for example, a magnetic sensor, etc. The type of the magnetic electronic device is not limited thereto.

[0058] The spin splitting-ferromagnetic coupling material in the present application is introduced below through specific embodiments.

[0059] In this embodiment, the spin splitting-ferromagnetic coupling material uses CdTe material as the spin splitting material, and uses W element as the doping element to prepare a W monolayer material of giant spin splitting magnetic material. 0.17 Cd 0.83 Te, this material has a large spin splitting energy, which is greater than 0.1eV, such as Figure 1 The spin splitting band structure diagram of the spin splitting material CdTe is shown.

[0060] Figure 2 The spin splitting-ferromagnetic coupling material W is shown in FIG. 0.17 Cd 0.83 Magnetic moment reversal curve of Te. Where m = M / M s , M is the magnetic moment of the material, M s is the saturation magnetic moment, and m is the normalized unitless magnetic moment.

[0061] Further, such as Figure 3This embodiment also provides a structural diagram of an MTJ manufactured using the spin splitting-ferromagnetic coupling material, wherein the magnetic tunnel junction includes a sandwich structure of a magnetic free layer 100 located at the top layer, a non-magnetic barrier layer 200 located at the middle layer, and a magnetic fixed layer 300 located at the bottom layer, wherein the magnetic free layer 100 is manufactured from the spin splitting-ferromagnetic coupling material. By applying an external electric field to flip the magnetic moment direction of the magnetic free layer 100 and the parallelism and antiparallelism of the magnetic moment between the magnetic fixed layer 300, the low resistance state and high resistance state of the magnetic tunnel junction can be formed, thereby achieving the purpose of information storage.

[0062] In this embodiment, the magnetic free layer 100 is a spin splitting-ferromagnetic coupling material having Dresselhaus spin splitting effect and ferromagnetism.

[0063] Further, such as Figure 4 This embodiment also provides an MRAM unit made using the spin splitting-ferromagnetic coupling material, including a top electrode 400, a magnetic free layer 100, a non-magnetic barrier layer 200, a magnetic fixed layer 300 and a bottom electrode 500, wherein the top electrode 400 is parallel to the bottom electrode 500, and the read and write paths are different, the read current passes through the magnetic tunnel junction, and the write current passes through the electrode.

[0064] Among them, Figure 4 The process of reading and writing data in the magnetic tunnel junction structure based on the spin splitting-ferromagnetic coupling material under the combined action of transverse and longitudinal currents is shown. The top electrode 400 is in direct contact with the magnetic free layer 100. When the memory writes information, the current 700 flows through the electrode 400, and the magnetic free layer 100 generates unbalanced spin accumulation at its interface, flipping the magnetic moment of the material itself to be parallel or anti-parallel to the magnetic moment of the magnetic fixed layer 300, and obtaining the low resistance state or high resistance state of the magnetic tunnel junction, thereby writing data into the storage unit. When reading information, a forward or reverse current 600 can be passed through the spin splitting-ferromagnetic coupling material. When it flows through the magnetic free layer 100, it flips the magnetic moment of this layer to be parallel or anti-parallel to the magnetic moment of the magnetic fixed layer 300, and obtains the low resistance state or high resistance state of the magnetic tunnel junction.

[0065] In summary, the spin splitting-ferromagnetic coupling material and its application of the present invention are obtained by doping the spin splitting material to obtain the spin splitting-ferromagnetic coupling material including the spin splitting material and the doping element, and the spin splitting-ferromagnetic coupling material has both energy band spin splitting and ferromagnetism, wherein the characteristic of energy band spin splitting lies in the spin splitting material, and the characteristic of ferromagnetism lies in the doping element. The spin splitting-ferromagnetic coupling material provided by the present invention can realize the all-electrical spin-orbit torque drive control to eliminate the heterostructure formed by the spin splitting material and the ferromagnetic material under the traditional spin-orbit torque, thereby simplifying the device structure prepared subsequently and reducing energy loss.

[0066] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A spin splitting-ferromagnetic coupling material, characterized in that: The spin splitting-ferromagnetic coupling material includes a spin splitting material and a doping element, and the spin splitting-ferromagnetic coupling material has both energy band spin splitting and ferromagnetism, wherein the characteristic of energy band spin splitting lies in the spin splitting material, and the characteristic of ferromagnetism lies in the doping element, and the spin splitting material includes one of BiTeI, COs, CdTe, HgTe, PtN2 and WN2; the doping element includes one or a combination of heavy elements or light elements that provide local asymmetric electrons; the heavy elements include Cr, Mn, Mo, W, V, Fe, Co, Ni, Pd and Sc, and the light elements include H, Li and B; the spin splitting-ferromagnetic coupling material is a fully electrically driven spin splitting-ferromagnetic coupling material, and the magnetic moment of the spin splitting-ferromagnetic coupling material is flipped by current regulation in the absence of an external magnetic field.

2. The spin splitting-ferromagnetic coupling material according to claim 1, characterized in that: The spin splitting energy of the spin splitting material is greater than 0.1 eV; the average atomic magnetic moment of the spin splitting-ferromagnetic coupling material is greater than 0.02 μ B / atom.

3. The electrically driven magnetic moment reversal method of the spin splitting-ferromagnetic coupling material according to claim 1, characterized in that: Added a step to assist with applied magnetic field.

4. A device structure, characterized in that: The device structure is prepared from the spin splitting-ferromagnetic coupling material described in any one of claims 1 to 3.

5. A magnetic tunnel junction, characterized in that: The magnetic tunnel junction comprises a magnetic free layer, a non-magnetic barrier layer and a magnetic fixed layer arranged from top to bottom, and the magnetic free layer is prepared from the spin splitting-ferromagnetic coupling material described in any one of claims 1 to 3.

6. An MRAM cell, characterized in that: The MRAM cell comprises a top electrode, the magnetic tunnel junction of claim 5 and a bottom electrode.

7. The MRAM cell according to claim 6, wherein: The top electrode is arranged in parallel with the bottom electrode, a read current passes through the magnetic tunnel junction, and a write current passes through the electrode.

8. A magnetic tunnel junction device, characterized in that: The magnetic tunnel junction device comprises the magnetic tunnel junction of claim 5.

9. An electronic device, characterized in that: The electronic device comprises the magnetic tunnel junction of claim 5.

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