A shear strain-controlled CrS 2 spin valve device and its control method

Abstract

The present invention discloses a shear strain-controlled CrS2 spin valve device, which is formed by parallel connection of two or more spin valve device units. Each spin valve device unit includes a substrate, a CrS2 layer and a protective layer disposed on the substrate, and is prepared by the following method: First, a 1T'-phase CrS2 layer is grown on the substrate; Second, a lateral heterojunction is regulated and formed; Third, a protective layer is grown on the lateral heterojunction; Fourth, a magnetic heterojunction is regulated and formed; The present invention also discloses a control method for the spin valve device unit: after connecting the spin valve device to an external circuit, a shear strain is applied to adjust the spin state of the spin valve device unit. Based on the ferroelasticity of CrS2 itself and the mutual coupling of ferromagnetism and ferroelasticity, the ferroelasticity of the 1T'-phase CrS2 layer is regulated by strain to further adjust its magnetic transition, solving the problem of matching different materials with different properties; the control method of the present invention is simple and easy to implement.

Description

Technical Field

[0001] The invention belongs to the technical field of material science and specifically relates to a shear strain controlled CrS 2 A spin valve device and a control method thereof. Background Art

[0002] In the face of the increasingly large computing and information processing tasks in the information age, whether the computing power of computer central processing units (CPUs) can continue to meet Moore's law has become a major concern and breakthrough point. The CPU manufacturing process has undergone 11 generations of optimization, from 0.5μm to the current 14nm, and is currently moving towards 10nm and 7nm. While the manufacturing process is constantly improving, it also provides more transistor layouts and lower energy consumption. However, as the miniaturization and integration of devices continue to increase, the device size approaches the physical limit, and the further improvement of CPU capabilities has fallen into a bottleneck. Spin electronics, which uses the spin properties of electrons as carriers for processing operations, has gradually become a key research field in the "post-Moore era". With the help of unique quantum effects such as giant magnetoresistance, tunnel magnetoresistance, topological insulators, and quantum spin Hall effect, spin electronic devices have become excellent carriers for the next generation of logic devices and quantum computing chips, with non-volatility, radiation resistance, high integration, high computing speed, and long life.

[0003] The research focus of spintronic devices for new CPUs is to utilize the coexistence of multiple quantum states of different spin orders of correlated electronic systems and their high controllability, realize the spatial controllable arrangement of different spin orders without chemical interfaces through external field confinement control, realize the integration of non-volatile spin storage and logic operations in the same material, and thus establish a new non-"von Neumann" spin information processing architecture. At present, spintronic devices mainly use ferromagnetic semiconductor / semimetal heterostructures, and control spin polarization reversal through magnetic field or spin momentum transfer to achieve spin injection, transport and detection. However, the high current density required by the device will lead to high energy consumption, and it is difficult to match different materials with each other, and the preparation is complicated. These problems have become a huge challenge in the research of spintronic devices. However, the current preparation of spin valves is to compound different materials and use the properties of different materials to work. This kind of device will bring many troubles during the preparation and use process, such as whether the crystal structures of different materials match during the preparation process, whether there is a high Schottky barrier at the interface of different materials, etc. Heterojunctions consisting of different phases of a single material can greatly avoid these problems, but this requires effective control of the phase structure and performance of the material. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a CrS shear strain controlled 2Spin valve device. The spin valve device is based on CrS 2 The inherent ferroelasticity and the mutual coupling of ferromagnetism and ferroelasticity can be used to regulate the 1T' phase CrS by strain. 2 The ferroelasticity of the layer further regulates its magnetic transition, forming a heterojunction of ferromagnetic and non-magnetic combination and orderly arrangement, obtaining a spin valve device unit which is then connected in parallel to form a spin valve device, solving the problem of matching different materials with different properties, reducing the types of materials used in the spin valve device and simplifying the structure.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a shear strain controlled CrS 2 Spin valve device characterized by more than two shear strain controlled CrS 2 The spin valve device units are connected in parallel, and the shear strain controlled CrS 2 The spin valve device unit includes a substrate, and a CrS 2 The layer and the protective layer are prepared by a method comprising the following steps:

[0006] Step 1: Growth of 1T' phase CrS on substrate 2 layer;

[0007] Step 2: 1T' phase CrS formed in step 1 by applying tensile and compressive strain 2 The formation of lateral heterojunctions with a combination of ferromagnetic and non-magnetic properties is regulated in the layers;

[0008] Step 3, growing a protective layer on the lateral heterojunction formed in step 2;

[0009] Step 4: By regulating the positive strain in step 3, an orderly arranged ferromagnetic / non-magnetic / ferromagnetic magnetic heterojunction is formed in the lateral heterojunction with a protective layer to obtain shear strain controlled CrS 2 Spin valve device unit.

[0010] The above-mentioned shear strain controlled CrS 2 The spin valve device is characterized in that the substrate and the protective layer are both SiC or GeC.

[0011] The above-mentioned shear strain controlled CrS 2 The spin valve device is characterized in that the growth in step 1 forms 1T' phase CrS 2 The layer is deposited by chemical vapor deposition.

[0012] In addition, the present invention also discloses a CrS for controlling the shear strain. 2 The control method of the spin valve device is characterized in that the process of the method is:2 The spin valve device is connected to an external circuit, and then shear strain is applied to the ferromagnetic regions on both sides of the magnetic heterojunction in the spin valve device unit to control the magnetization orientation of the ferromagnetic regions on both sides of the magnetic heterojunction and adjust the spin state of the spin valve device unit.

[0013] The above method is characterized in that when the magnetization orientations of the ferromagnetic regions on both sides of the magnetic heterojunction are the same, the spin-polarized electrons with the same magnetization orientation are conducted, and when the magnetization orientations of the ferromagnetic regions on both sides of the magnetic heterojunction are different, no spin-polarized electrons are conducted.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. The present invention is based on CrS 2 The inherent ferroelasticity and the mutual coupling of ferromagnetism and ferroelasticity can be used to regulate the 1T' phase CrS by strain. 2 The ferroelasticity of the layer regulates its magnetic transition and forms CrS 2 The ferromagnetic and non-magnetic layers are combined and orderly arranged in a heterojunction, and the shear strain-controlled CrS 2 The spin valve device units are then connected in parallel to form a spin valve device, which solves the problem of matching different materials with different properties, reduces the types of materials used in the spin valve device and simplifies the structure.

[0016] 2. Compared with the traditional spin valve device which relies on magnetic field to drive magnetization orientation and has the disadvantage of high energy consumption, the spin valve device of the present invention relies on CrS 2 The multi-magnetic and magnetoelastic coupling is achieved by controlling the formation of the spin valve device through local positive strain, and the magnetization orientation of the magnetic region is controlled by shear strain, which effectively reduces the energy consumption, and the control process is simpler and easier to implement.

[0017] 3. The present invention connects more than two spin valve device structural units in parallel, so that the spin valve device units in each parallel branch show different electronic conduction states and are defined as different logic signals, thereby forming a spin valve device with a computing unit to realize logic operations, which has broad application prospects.

[0018] 4. The present invention can realize the control of the spin valve device only by adopting shear strain, which is simple, reliable and easy to realize, and has great application potential in the fields of logic operation and information storage.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 CrS in the present invention 2 Schematic diagram of different ferroelastic domain orientations in 1T phase and 1T' phase.

[0021] Figure 2 The CrS controlled by shear strain of the present invention 2 A diagram showing the relationship between magnetization orientation and shear strain of a spin valve device unit.

[0022] Figure 3 CrS controlled by shear strain of the present invention 2 1T' phase CrS in spin valve device unit 2 Phase diagram of the relationship between biaxial strain magnetism and non-magnetism of the layer.

[0023] Figure 4a The CrS controlled by shear strain of the present invention 2 Schematic diagram of the structure of a spin valve device unit.

[0024] Figure 4b CrS controlled by shear strain of the present invention 2 Schematic diagram of applying shear strain in a spin valve device unit.

[0025] Figure 5 CrS controlled by shear strain of the present invention 2 Schematic diagram of the control process of the spin valve device unit. DETAILED DESCRIPTION

[0026] Example 1

[0027] like Figure 1 As shown in (a), CrS 2 The 1T phase is an antiferromagnetic phase, which is a high-symmetry phase without structural anisotropy.

[0028] like Figure 1 As shown in (b), (c), and (d), CrS 2 The 1T' phase of CrS has three different structural orientations, namely 1T'-O1, 1T'-O2 and 1T'-O3, which can be regarded as three different ferroelastic domains. 2 The 1T' phase is equivalent to the distortion of the 1T phase. The ratio of the Cr atomic spacing has changed, and d 1 / d 2 <1, while the angle between the 1T' phase ferroelastic domains in the three structural orientations is about 120°.

[0029] like Figure 2 As shown in (a), due to CrS 2 The three ferroelastic domains in the 1T' phase have magnetic anisotropy. The initial magnetization orientation is set to the (010) direction. The magnetic anisotropy is calculated by changing the angle between the magnetic moment and the (010) direction. The relevant results are shown in (b).

[0030] like Figure 2As shown in (b) in the figure, as the angle between the magnetic moment and the (010) direction continues to change, the lowest values ​​of the magnetic anisotropy energy of the three ferroelastic domains are related to their respective domain orientations. Correspondingly, the lowest energy angles in 1T'-O1, 1T'-O2 and 1T'-O3 (equivalent to O1, O2 and O3 in the figure) are 0° (180°), 120° and 60°, respectively.

[0031] from Figure 1 and Figure 2 It can be seen that CrS 2 The 1T' phase of CrS has ferroelasticity, and there is a mutual coupling relationship between ferromagnetism and ferroelasticity. 2 The ferroelasticity of the 1T' phase changes its ferromagnetic potential.

[0032] exist Figure 1 and Figure 2 Based on the content, the present invention is to 1T' phase CrS 2 The relationship between the biaxial strain magnetism and non-magnetism of the layer was studied, and the results are shown in the figure Figure 3 As shown. Figure 3 It can be seen that through the 1T' phase CrS 2 Different strains are applied in the x-axis and y-axis directions of the layer, that is, by 2 The tensile or compressive strain of the layer can effectively adjust and control the 1T' phase CrS 2 Regions of the layer are either ferromagnetic (FM) or nonmagnetic (NM).

[0033] The shear strain controlled CrS of this example 2 Spin valve devices controlled by more than two shear strains in CrS 2 The spin valve device units are connected in parallel, and the shear strain controlled CrS 2 The spin valve device unit includes a substrate, and a CrS 2 The layer and the protective layer are prepared by a method comprising the following steps:

[0034] Step 1: Growth of 1T' phase CrS on substrate 2 layer;

[0035] Step 2: 1T' phase CrS formed in step 1 by applying tensile and compressive strain 2 The formation of lateral heterojunctions with a combination of ferromagnetic and non-magnetic properties is regulated in the layers;

[0036] Step 3, growing a protective layer on the lateral heterojunction formed in step 2;

[0037] Step 4: By regulating the positive strain, an orderly arranged ferromagnetic / non-magnetic / ferromagnetic magnetic heterojunction is formed in the lateral heterojunction formed in step 2 to obtain shear strain controlled CrS 2 Spin valve device unit.

[0038] based on Figure 1 to Figure 3 The present embodiment adopts more than two shear strain controlled CrS 2 Spin valve device units are connected in parallel to obtain shear strain-controlled CrS 2 Spin valve device, in which shear strain controls the CrS 2 The spin valve device unit consists of a substrate, CrS 2 layer and protective layer, such as Figure 4a As shown, in the process of preparing the spin valve device unit, 1T' phase CrS 2 The ferroelasticity of the 1T' phase CrS 2 The tensile and compressive strains are applied to the layer to regulate and control the 1T' phase CrS 2 The region of the layer is transformed into ferromagnetic and non-magnetic, forming a lateral heterojunction of ferromagnetic and non-magnetic combination, and then the 1T' phase CrS is regulated by positive strain. 2 The orderly arrangement of the ferromagnetic region and the non-magnetic region in the layer forms a ferromagnetic / non-magnetic / ferromagnetic magnetic heterojunction, and the shear strain-controlled CrS 2 Spin valve device unit. During the use of the spin valve device unit, the magnetization orientation of different ferromagnetic regions is changed to be the same or different by applying local shear strain, thereby controlling the conduction state of the spin polarized current in the external circuit, thereby achieving the regulation of the performance of the same material by different phases, avoiding the problem of matching different materials with different properties; at the same time, the types of materials used in the spin valve device are reduced, and the structure of the spin valve device is simplified.

[0039] At the same time, this embodiment combines more than two shear strain controlled CrS 2 The spin valve device units are connected in parallel to obtain the shear strain controlled CrS2 spin valve device. 2 The conduction state of the spin valve device unit corresponds to different conduction states and is defined as different logic signals, forming multiple calculation unit logic operation devices to realize logic operation functions and information storage functions.

[0040] Furthermore, the substrate and the protective layer in this embodiment are both SiC or GeC. The above semiconductor or insulating layer substrate is usually selected as the substrate to support and protect the core material CrS of the spin valve device unit. 2 The role of layers.

[0041] The above-mentioned shear strain controlled CrS2 spin valve device is characterized in that the growth of the 1T' phase CrS in step 1 2 The method of forming the layer is chemical vapor deposition. The present invention can form 1T' phase CrS on the substrate by conventional forming methods. 2 Layer, the method is simple and easy to implement.

[0042] The control method of the shear strain controlled CrS2 spin valve device unit in this embodiment is as follows: 2 The spin valve device is connected to an external circuit, and then shear strain is applied to the ferromagnetic regions on both sides of the magnetic heterojunction in the spin valve device unit, such as Figure 4b As shown, by setting stress loading devices in the ferromagnetic regions on both sides of the magnetic heterojunction, and using the stress loading devices in different regions to move and apply different shear strains, the magnetization orientation of the ferromagnetic regions on both sides of the magnetic heterojunction can be controlled, thereby adjusting the spin state of the spin valve device unit.

[0043] In this embodiment, the shear strain-controlled CrS2 spin valve device is connected to an external circuit to pass a non-spin polarized current, and then shear strain is applied to the ferromagnetic regions on both sides of the magnetic heterojunction in the spin valve device unit to change the magnetization orientation, so that the respective parallel spin valve device units are in different electronic conduction states, that is, different spin states. Specifically, when the magnetization orientations of the ferromagnetic regions on both sides of the magnetic heterojunction are the same and remain consistent with the spin-up direction, the spin valve device unit only conducts the spin-up polarized current, such as Figure 5 As shown in (a) in FIG. 1 , when the magnetization orientations of the ferromagnetic regions on both sides of the magnetic heterojunction are the same and remain consistent with the spin-down direction, the spin valve device unit only conducts the spin-down polarization current, such as Figure 5 As shown in (b), when the magnetization orientations of the ferromagnetic regions on both sides of the magnetic heterojunction are opposite, no current is conducted, such as Figure 5 As shown in (c) in the figure. Therefore, the control process of this embodiment applies shear strain to make the spin valve device unit in different spin states, so that the polarization current conducted is different, and the corresponding signals detected in the external circuit are also different. Then, different logic signals are defined according to the detected signals, such as defining the conduction spin-up polarization current state as "1", defining the conduction spin-down polarization current state as "-1", and defining the non-conducting current state as "0", forming multiple calculation unit logic operation devices to realize logic operation functions and information storage functions.

[0044] Furthermore, in this embodiment, when the magnetization orientations of the ferromagnetic regions on both sides of the magnetic heterojunction are the same, the spin-polarized electrons with the same magnetization orientation are conducted; when the magnetization orientations of the ferromagnetic regions on both sides of the magnetic heterojunction are different, no spin-polarized electrons are conducted.

[0045] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A shear strain-controlled CrS 2 spin valve device It is characterized in that CrS controlled by more than two shear strains 2 spin valve device units are connected in parallel, and the shear strain-controlled CrS 2 spin valve device unit includes a substrate, and a CrS layer and a protective layer sequentially arranged on the substrate from bottom to top, and is prepared by a method including the following steps: 2 ​ Step 1: Grow a 1T'-phase CrS layer on the substrate 2 layer; Step 2: Modulate the 1T'-phase CrS formed in Step 1 by applying tensile and compressive strains 2 in the layer, such that the 1T'-phase CrS 2 layer undergoes a ferromagnetic state change without a phase transition, forming a lateral heterojunction composed of ferromagnetic and non-magnetic regions; Step 3: A protective layer is grown on the laterally heterojunction formed in Step 2; Step 4: By using the normal strain to regulate the formation of an orderly arranged ferromagnetic / non-magnetic / ferromagnetic magnetic heterojunction in the lateral heterojunction with a protective layer in Step 3, a shear strain-controlled CrS 2 spin valve device unit is obtained.

2. A shear strain-controlled CrS 2 spin valve device, It is characterized in that Both the substrate and the protective layer are SiC or GeC.

3. A shear strain-controlled CrS 2 spin valve device, It is characterized in that The method for growing and forming the 1T'-phase CrS 2 layer in Step 1 is chemical vapor deposition method.

4. A control method for a spin valve device with shear strain control as described in any one of claims 1 to 3 2 ​ It is characterized in that The process of this control method is as follows: Connect the shear strain-controlled CrS 2 spin valve device to an external circuit, and then apply shear strain to the ferromagnetic regions on both sides in the magnetic heterojunction in the spin valve device unit to control the magnetization orientation of the ferromagnetic regions on both sides in the magnetic heterojunction and adjust the spin state of the spin valve device unit.

5. The method according to claim 4, It is characterized in that When the magnetization orientations of the ferromagnetic regions on both sides in the magnetic heterojunction are the same, it conducts the spin-polarized electrons with the same magnetization orientation, and when the magnetization orientations of the ferromagnetic regions on both sides in the magnetic heterojunction are different, it does not conduct any spin-polarized electrons.

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