A two-dimensional antiferromagnetic tunnel junction

Abstract

The application provides a novel two-dimensional antiferromagnetic tunnel junction, AFMTJ, which is an ultra-thin AFMTJ composed of two magnetic vdW electrodes FGT and a single-layer CIPS sandwiched between the two magnetic vdW electrodes FGT. The application also provides a method for simulating the construction of the two-dimensional antiferromagnetic tunnel junction, which comprises the following steps: cutting the FGT and the CIPS in the (001) direction to obtain a single-layer structure of the FGT and the CIPS, and expanding the cell and stacking the single-layer FGT and the single-layer CIPS to form the two-dimensional antiferromagnetic tunnel junction. The tunnel junction can be used to change the polarization of the CIPS and further control the performance of the tunneling device, and has great application potential in non-volatile storage.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microelectronics, in particular to a two-dimensional antiferromagnetic tunnel junction device. BACKGROUND

[0002] Tunnel junction is an important electronic device for information storage and processing, in which electrons can be transported through an insulating layer due to the electron tunneling effect. Controllable tunneling resistance is the basis of application, and two implementation methods have been proposed: ferromagnetic tunnel junction (MTJ) and ferroelectric tunnel junction (FTJ). In MTJ, the conductive layer is a ferromagnetic (FM) material. The tunneling resistance of MTJ can be changed by changing the magnetic arrangement of the two ferromagnetic layers between parallel (P) and anti-parallel (AP) arrangements, which is called tunneling magnetoresistance (TMR) effect. While in FTJ, the middle insulating layer is a ferroelectric material, and both sides have asymmetric conductive layers. Due to different interactions with the electrodes, changing the polarization of the ferroelectric layer will also change the tunneling resistance of the FTJ, which is called tunneling resistance (TER) effect. Large current transformers require significant differences between the two electrodes. In addition, the asymmetry of the two conductive layers produces a strong built-in electric field, which is not conducive to polarization reversal.

[0003] A new concept has recently been proposed: using AFE insulating layers and controlling the tunneling resistance by switching the FE and AFE states of the insulating layer, called antiferromagnetic tunnel junction (AFTJ). In addition to the antiferromagnetic tunnel junction (AFTJ), the concept of multi-ferroelectric tunnel junction (MFTJ) has also been proposed. Multi-ferroelectric tunnel junction (MFTJ) has a ferromagnetic / ferroelectric / ferromagnetic structure, and has both tunneling magnetoresistance and electroresistance effects, which has potential application value in multi-resistance state non-volatile information storage and other aspects.

[0004] Traditional devices such as MTJ / FTJ are thin films made of three-dimensional (3D) materials, which have many problems. One of the most prominent problems is that the interface between the insulating layer and the conductive layer will affect the transmission of electrons, and defects are usually present at the interface to inhibit electron transmission. In addition, the diffusion and oxidation of elements at the interface are also not conducive to electron transmission. On the other hand, device miniaturization is very important for application, but it is still difficult to control the thickness of 3D materials. In addition, for most 3D FE thin films, when the thickness is lower than a critical value, the polarization disappears, which leads to the failure of FTJ. In addition, due to strong bonding, non-volatile AFE-FE switching in 3D materials is almost impossible, so 3D AFTJ is still in a blank state. On the other hand, low RA (resistance-area product) products are very important for tunnel junctions. For example, a recording density of about 200 Gbit / in 2 requires an RA product of less than 1Ω·μm 2However, in the conventional 3D tunnel junction, the RA product of the RA device is usually large, such as a multi-ferroelectric tunnel junction (MFTJ) which usually uses a perovskite oxide material as a ferroelectric barrier layer, and the resistance-area product (RA) is usually large, which limits their application in practical devices.

[0005] In recent years, many two-dimensional van der Waals (vdW) FM (ferromagnetic) and FE (ferroelectric) materials have been predicted and discovered, providing a broad platform for two-dimensional MTJ and FTJ. Due to the vdW interaction between adjacent layers, it can overcome many problems of the above-mentioned 3D tunnel junction, such as interface bonding, defect diffusion and interface oxidation. In addition, these 2D vdW materials are easy to exfoliate into multiple layers, and sometimes even into single layers, which are ideal materials for device miniaturization.

[0006] At present, a small number of 2D vdW MTJs or FTJs have been designed and manufactured in experiments, and recently researchers have designed a two-dimensional multi-ferroelectric tunnel junction combining the characteristics of MTJ and FTJ. However, the device combining two-dimensional AFTJ and MTJ is still basically in a blank state. SUMMARY

[0007] Based on the above problems in the prior art, the present application designs a new type of tunnel junction, a two-dimensional antiferromagnetic tunnel junction (2D AFMTJ) combining the device characteristics of two-dimensional AFTJ and MTJ. This two-dimensional AFMTJ has a large TER and TMR ratio and has an ultra-low RA product, which opens up a new way for realizing nanoscale storage devices with ultra-high storage density.

[0008] To achieve the above-mentioned application purposes, the present application adopts the following technical solutions.

[0009] The present application provides a new type of two-dimensional antiferromagnetic tunnel junction (2D AFMTJ), which comprises two magnetic vdW electrodes Fe3GeTe2 (FGT) and a CuInP2S6 (CIPS) single layer sandwiched between the two magnetic vdW electrodes Fe3GeTe2, wherein the two magnetic vdW electrodes Fe3GeTe2 adopt a single layer of FGT.

[0010] Fe3GeTe2 is a metallic ferromagnetic material with high Curie temperature, good air stability under atmospheric conditions, and two stable magnetization structures FM and AFM, and strong magnetic anisotropy. And Fe3GeTe2 is a typical vdW material, which remains ferromagnetic in the single-layer limit. The space group of Fe3GeTe2 is P63 / mmc, and the lattice constant measured by experiment is a = 3.99 Å, c = 16.33 Å. The "sandwich" structure of vdW Fe3GeTe2 is weakly bound to each other through van der Waals interaction. It is found that there may be a large number of Fe-II vacancies in the FeGe layer, and bulk Fe3GeTe2 has a relatively high magnetic order temperature and a large anisotropy. More importantly, Fe3GeTe2 has interlayer ferromagnetic (FM) order, and when a lower magnetic field is used, the magnetization of Fe3GeTe2 exhibits interlayer antiferromagnetic (AFM) ordering.

[0011] CuInP2S6 is a room-temperature ferroelectric semiconductor with a band gap of 2.2 eV, and the ferroelectricity of CuInP2S6 is derived from the structural distortion of Cu ions and In ions in the sulfur octahedron. Below the Curie temperature of CuInP2S6, Cu ions will be asymmetrically distributed near the Cu1 site deviating from the center, resulting in spontaneous polarization. By applying a voltage, the polarization order of CIPS can be switched between AFE and FE states. When a larger external electric field than the coercive field of CuInP2S6 is applied, for example, the electric field downward, the external electric field will cause the displacement of Cu ions and In ions in the material, thereby forming an electric dipole moment, which macroscopically exhibits polarization in the downward direction. In an independent CuInP2S6 monolayer, the AFE state is the ground state, and the free energy of the FE state is about 48 meV higher than that of the AFE state. Although the AFE state is the ground state of the independent CIPS monolayer, the interaction with the electrode can change the energy difference between the ferroelectric state and the antiferromagnetic state, thereby obtaining different ground states. And CIPS is also a typical vdW FE material, and its switchable room-temperature out-of-plane polarization has been experimentally verified in bulk and nanosheets.

[0012] The thickness of the ultra-thin CIPS monolayer film is far below the critical size of most FE perovskite oxide thin films, and is very promising for application in small FE devices. CIPS can be relatively easily combined with FGT to form a heterostructure due to the relatively inert atomic surface and vdW interlayer interaction, and further form a vertical vdW heterostructure device with the required function. Importantly, the use of CIPS, a room-temperature antiferromagnetic material, as an intermediate insulating layer, can obtain a larger TER without the need for a significant difference between the two electrodes, avoiding the strong built-in electric field caused by the asymmetry of the two conductive layers, making the polarization reversal easy. Therefore, the vdW Fe3GeTe2 / CuInP2S6 / Fe3GeTe2 three-layer heterostructure is used in the scattering region, and the tunnel junction prepared has an extremely thin thickness, and can maintain a strong magnetoelectric coupling at room temperature, and importantly, can obtain a larger TMR and TER and a smaller RA, thereby having good tunneling performance.

[0013] The present application uses a vdW Fe3GeTe2 / CuInP2S6 / Fe3GeTe2 tunnel junction, and in the calculation structure model, a heterostructure is constructed by sandwiching a CIPS monolayer between two FGT magnetic electrodes, and a vacuum layer with a length of 20 angstroms or more in the Z direction is used in the direction perpendicular to the sheet. Since both electrodes are Fe3GeTe2, there is no mismatch caused by asymmetric electrodes, and therefore Fe3GeTe2 / CuInP2S6 / Fe3GeTe2 has a relatively high transmission rate.

[0014] Further, FGT and CIPS both have a hexagonal crystal structure, and the lattice constant matching is good, and the present application forms a two-dimensional antiferromagnetic magnetic tunnel junction by expanding the cell stacking of the vdW FGT and the monolayer CIPS, so that the lattice mismatch between the two is less than 3%. Further, the vdW FGT and the monolayer CIPS can be stacked in different ways, and when one of the systems is rotated by a certain angle, the tunnel junction has different properties. In the embodiment of the present application, the monolayer FGT is constructed in the XY plane 3 supercells, the monolayer CuInP2S6 is constructed in the XY plane 2 supercells, and the cell is expanded and stacked, and at this time, the lattice mismatch rate between the two is between 2.2-2.3%, and the initial distance between the monolayer Fe3GeTe2 and the monolayer CuInP2S6 is set to 3-3.5 angstroms, and the length of the vacuum layer added in the Z direction (perpendicular to the sheet direction) is 20 angstroms or more. When the monolayer CuInP2S6 is combined with FGT to form a tunnel junction in a ferroelectric state, the monolayer FGT is constructed in the XY plane 3 supercells, the monolayer CuInP2S6 is constructed in the XY plane 2 supercell, the total number of atoms in the stacked structure is 148. The tunnel junction of single-layer CuInP2S6 in the antiferroelectric state and single-layer FGT will first change the two systems from hexagonal to orthorhombic, and then expand the cell to stack, and the single-layer FGT is constructed in the XY plane 3 3 supercell, single-layer CuInP2S6 in the antiferroelectric state is constructed 2 2 supercell, the total number of atoms in the stacked structure is 296.

[0015] After the tunnel junction of the CIPS single layer sandwiched between two vdW FGT magnetic electrodes is constructed, there is a charge transfer between CuInP2S6 and Fe3GeTe2, which can be determined by calculating the density of states of CuInP2S6 and Fe3GeTe2 and analyzing the charge. At this time, the ground state of the independent CIPS single layer will change, and the isolated single layer of CIPS is insulating in the FE and AFE states, but when the charge transfer between the electrode occurs, the single-layer CuInP2S6 will become a conductor. In addition, the charge transfer between CIPS and the electrode has great significance for the interface structure, that is, the vertical distance between the Cu ion and the Te plane at the interface will change. CuInP2S6 in the ferroelectric state, Cu atoms are located on one side of CIPS, and the upper and lower FGT / CIPS interfaces are asymmetric; while in the antiferroelectric state, Cu atoms are symmetrically distributed on both sides of CIPS, the two FGT / CIPS interfaces are equivalent, and the total transmission performance is better.

[0016] The transmission function can be expressed as:

[0017]

[0018] Where σ is the spin, k||= (kx, ky) is the wave vector in the two-dimensional Brillouin zone; 、 And The transmission functions of the upper and lower interfaces and the middle layer are represented respectively. RA is inversely proportional to the transmission function, which can be expressed as:

[0019]

[0020] Where A is the unit cell area, T(Ɛ F ) is the transmission function at the Fermi level, Unlike other tunnel junctions, the tunnel junction constructed by Fe3GeTe2 / CuInP2S6 / Fe3GeTe2 can have a smaller RA.

[0021] TMR and TER of Fe3GeTe2 / CuInP2S6 / Fe3GeTe2 tunnel junction can be obtained by the following formula

[0022] TMR = |G P - G AP | / min(G P , G AP )

[0023] TER = | G FE – G AFE | / min(G FE , G AFE )

[0024] Where GP and GAP are the conductance of Fe3GeTe2 with parallel and antiparallel magnetic order, respectively; GFE and GAFE are the conductance of CuInP2S6 in ferroelectric and antiferroelectric states, respectively. Fe3GeTe2 / CuInP2S6 / Fe3GeTe2 tunnel junction can obtain larger TMR and TER without the need for two electrodes or two interfaces with significant differences.

[0025] The Fe3GeTe2 / CuInP2S6 / Fe3GeTe2 three-layer heterostructure two-dimensional antiferromagnetic tunnel junction not only solves the critical thickness problem of three-dimensional ferroelectric materials, reduces the size of the ferroelectric tunnel junction memory, and most importantly, can obtain larger TMR and TER and smaller RA, thereby having good tunneling performance, and has great application potential in non-volatile storage. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The hysteresis loops of the thicker FGT under the protection of BN at different temperatures (60-190K) measured by the MOKE system, and the exchange bias phenomenon is weakened with the increase of temperature.

[0027] Figure 2 The hysteresis loops of the thicker FGT under the protection of BN at different temperatures (below 50K) measured by the MOKE system.

[0028] Figure 3 Different stacking modes of single-layer FGT and single-layer ferroelectric CIPS.

[0029] Figure 4 One of the different stacking structures of single-layer FGT and single-layer antiferromagnetic CIPS.

[0030] Figure 5 One of the different stacking structures of single-layer FGT and single-layer antiferromagnetic CIPS.

[0031] Figure 6 One of different stack structures of single-layer FGT and single-layer antiferromagnetic state CIPS. DETAILED DESCRIPTION

[0032] The present application will be further described below in conjunction with the accompanying drawings and specific examples. However, it should be understood that these examples are merely used to more specifically illustrate the use, and should not be understood as limiting the present application in any form.

[0033] The inventors constructed a new two-dimensional antiferromagnetic magnetic tunnel junction (2D AFMTJ) by calculation and simulation, etc. The two-dimensional AFMTJ includes two magnetic vdW electrodes Fe3GeTe2 (i.e. FGT), and a CuInP2S6 single layer sandwiched between the two magnetic vdW electrodes Fe3GeTe2.

[0034] Based on the characteristics of the vdW FGT and the single-layer CIPS, a heterostructure is constructed by sandwiching the CIPS single layer between the two vdW FGT magnetic electrodes, and a two-dimensional antiferromagnetic magnetic tunnel junction is obtained by the Fe3GeTe2 / CuInP2S6 / Fe3GeTe2 three-layer heterojunction structure. Through first-principle calculation and model testing, the two-dimensional antiferromagnetic magnetic tunnel junction constructed by the present application has a very thin thickness compared with general tunnel junctions, and can maintain a strong magnetoelectric coupling at room temperature, can obtain a large TMR and TER and a small RA, and has a good tunneling performance.

[0035] Specific operation examples are as follows.

[0036] Example 1

[0037] (1) Select thin-layer vdW Fe3GeTe2 and single-layer CuInP2S6 (CIPS) to form a two-dimensional ferromagnetic and ferroelectric material of a tunnel junction. In this embodiment, thin-layer vdW Fe3GeTe2 is selected as a two-dimensional ferromagnetic material of a heterojunction with single-layer CIPS based on the following research on FGT. The specific process is as follows.

[0038] The discovery of two-dimensional (2D) van der Waals (vdW) ferromagnets provides an interesting platform for studying low-dimensional magnetic phenomena, and more and more 2D vdW ferromagnets are predicted, but few can reach Curie temperature (Tc) or above room temperature. Among various types of quasi-two-dimensional ferromagnetic materials, the inventors of the present application selected Fe3GeTe2 (FGT) as a two-dimensional ferromagnetic material to form a heterojunction with a single-layer CIPS. FGT exhibits a relatively high Tc (Tc around 200K) and good stability when exposed to air. In vdW ferromagnets, the exchange coupling between layers can be very different due to the different interatomic layer distances. Many researchers believe that FGT is a stable ferromagnetic (FM), and a small number of studies have shown that FGT has antiferromagnetic properties. In the inventors' tests, FGT was found to have ferromagnetic properties, and thin layers and a large number of layers were all ferromagnetic, and the ferromagnetic properties were enhanced with the increase of the number of layers. On this basis, the present application further tests FGT.

[0039] Exchange bias is a kind of effect widely existing at the interface of ferromagnetic / antiferromagnetic materials, which macroscopically shows the shift of the hysteresis loop relative to the zero field, and microscopically the exchange bias is derived from the exchange coupling of the uncompensated magnetic moment at the interface. Without an external field, the magnetic moment of the antiferromagnetic layer is randomly arranged. Under different external fields, the anisotropy of the antiferromagnetic layer is large and does not change with the external field, but the ferromagnetic layer will reverse with the external field. The interface antiferromagnetic layer will produce pinning effect on the interface ferromagnetic layer, so that the magnetic moment of the ferromagnetic layer must overcome this pinning effect to reverse.

[0040] The present application uses a MOKE and Hall system based on an Oxford low-temperature magnet to test Fe3GeTe2 (FGT). The MOKE system is based on the magneto-optical Kerr effect, that is, after linearly polarized light is incident on the magnetic material and reflected, due to the difference in propagation speed of left-handed circularly polarized light and right-handed circularly polarized light in the sample, a phase difference is generated, and then the amplitude difference is caused by the difference in absorption of left-handed circularly polarized light and right-handed circularly polarized light. After reflection by the sample, it becomes elliptically polarized light. The principle of the Hall system is the anomalous Hall effect, which is completely different in nature from the ordinary Hall effect, because there is no Lorentz force of the external magnetic field on the electron to produce the motion trajectory deflection. This Hall effect in zero magnetic field is the anomalous Hall effect. The present application tests the hysteresis loop of FGT under the protection of BN, such as Figure 1 and Figure 2The magnetic hysteresis loop of FGT measured by the MOKE system is shown. It is found that the exchange bias phenomenon occurs in the case of thick FGT protected by BN (boron nitride), and the exchange bias phenomenon weakens as the temperature rises, and disappears when the temperature rises to about 100K. When the thick FGT is not protected and exposed to air, the exchange bias phenomenon is weak. The thin layer FGT is also studied in the application, and there is no exchange bias phenomenon when the thin layer FGT is protected or directly exposed to air. Further, the application studies the use of CIPS to protect FGT, and finds that the effect is similar to BN, and the exchange bias phenomenon occurs in the case of thick FGT, and there is no exchange bias phenomenon in the thin layer vdW FGT.

[0041] (2) Obtain the lattice constant of FGT and CIPS and calculate after optimization. The lattice constant of FGT is: a=3.99 Å, c=16.33 Å, Fe3GeTe2 is a van der Waals layered structure, the space group is P63 / mmc, and the thickness of single-layer Fe3GeTe2 is between 5.5-5.7 Å; the lattice constant of CIPS is 6.12 Å, and the thickness of single-layer is between 3.3-3.5 Å.

[0042] (3) Obtain thin layer vdW Fe3GeTe2 and single-layer CIPS: cut Fe3GeTe2 and CuInP2S6 in the (001) direction to obtain thin layer vdW FGT (FGT single layer) and CuInP2S6 single layer structure, respectively having 6 and 10 atoms.

[0043] (4) The thin layer vdW FGT and CIPS single layer structure obtained in step (3) are expanded and stacked to form the two-dimensional antiferromagnetic tunnel junction of the application, so that the lattice mismatch is less than 3%.

[0044] The FGT single layer is constructed in the XY plane 3 supercell, CuInP2S6 single layer is constructed 2 2 supercell is expanded and stacked, at this time the lattice mismatch rate of the two is between 2.2-2.3%, the initial distance between the single-layer Fe3GeTe2 and the single-layer CuInP2S6 is set to 3-3.5 Å, and the length of the vacuum layer added in the Z direction (perpendicular to the sheet direction) is more than 20 Å. When the CuInP2S6 single layer is in the ferroelectric state, a tunnel junction is constructed with the single-layer FGT, and the stacking mode of the two can adopt any one of the stacking structures in a, b, or c Figure 3 Figure 3 ​Preferred stacking structure of FIG. 2. When CuInP2S6 monolayer is in antiferroelectric state, tunnel junction is constructed with monolayer FGT, first, the two systems are converted from hexagonal system to orthorhombic system, then the same monolayer FGT is constructed in XY plane to form 3 3 supercell, monolayer CuInP2S6 is constructed to form 2 2 supercell, and the stacking mode can adopt any one of the stacking structures in FIGS. Figure 4 、 Figure 5 or Figure 6 , and the stacking structure formed has 296 atoms. The preferred stacking structure in FIG. 3 is adopted in this embodiment. Figure 4

[0045] When monolayer CuInP2S6 is constructed with monolayer Fe3GeTe2 to form a tunnel junction, in ferroelectric state, adjacent Cu ions in CuInP2S6 move in the same direction; and in antiferroelectric state, adjacent Cu ions in CuInP2S6 move in opposite directions. Therefore, in ferroelectric state, Cu atoms are located on one side of CIPS, and the upper and lower two FGT / CIPS interfaces are asymmetric; and in antiferroelectric state, Cu atoms are symmetrically distributed on both sides of CIPS, the two FGT / CIPS interfaces are equivalent, and the total transmission performance is better.

[0046] For the two-dimensional antiferromagnetic tunnel junction constructed by monolayer CuInP2S6 and monolayer Fe3GeTe2, the quantum mechanical model based on electron transport is used for measurement and calculation, and it is proved that the antiferromagnetic tunnel junction constructed by the application has considerable tunneling resistance effect, multiple non-volatile resistance states, and a very low RA product. RA, TMR and TER are measured and calculated as follows.

[0047]

[0048] where A is the unit cell area, T(Ɛ F ) is the transmission function at the Fermi level, .

[0049] TMR = | G P - G AP | / min(G P , G AP )

[0050] TER = | G FE - G AFE | / min(G ​FE , G AFE )

[0051] where GP and GAP are the conductance of Fe3GeTe2 with parallel and antiparallel magnetic order, respectively; GFE and GAFE are the conductance of CuInP2S6 in ferroelectric and antiferroelectric state, respectively.

[0052] The anti-ferromagnetic tunnel junction constructed in Example 1 is measured and calculated, and the measurement and calculation results are obtained, wherein the TMR is above 100%, the TER is above 90%, the RA is 0.1Ω·μm 2 The test results show that the two-dimensional anti-ferromagnetic tunnel junction (AFMTJ) provided by the application is superior to the conventional MFTJ in the application of non-volatile memory, and provides a new way for the application of nanometer memory devices.

[0053] The above is a detailed description of the best embodiment of the application, but it is obvious that researchers in the technical field of the application can make non-essential changes in form and content according to the above steps without deviating from the scope of the application. Therefore, the application is not limited to the above specific forms and details.

Claims

1. A model construction of a two-dimensional antiferromagnetic tunnel junction, characterized by, The two-dimensional antiferromagnetic tunnel junction comprises two magnetic vdW electrodes FGT, and a single-layer CIPS sandwiched between the two magnetic vdW electrodes Fe3GeTe2; wherein the magnetic vdW electrode FGT adopts a single-layer FGT; The model construction comprises the following steps: 1) selecting a thin-layer vdW FGT, i.e., a single-layer FGT, and a single-layer CIPS as two-dimensional ferromagnetic and ferroelectric materials for constructing the two-dimensional antiferromagnetic tunnel junction; 2) obtaining the lattice constants of FGT and CIPS and performing calculation after optimization; 3) obtaining the single-layer FGT and the single-layer CIPS; 4) expanding the cells and stacking the single-layer FGT and the single-layer CIPS obtained in step 3) to form the two-dimensional antiferromagnetic tunnel junction, so that the lattice mismatch between the two is less than 3%; 5) measuring and calculating the performance parameters RA, TMR and TER of the two-dimensional antiferromagnetic tunnel junction.

2. The model of a two-dimensional antiferromagnetic tunnel junction according to claim 1, wherein: In step 2), the FGT lattice constant is taken as FGT is a van der Waals layered structure with space group P63 / mmc; the lattice constant of the CIPS is taken as 3. The model of a two-dimensional antiferromagnetic tunnel junction of claim 1, wherein, The obtaining of the single-layer FGT and the single-layer CIPS in step 3) is: cutting FGT and CIPS in the (001) direction to obtain single-layer FGT and CIPS, i.e., the single-layer FGT and the single-layer CIPS, which respectively have 6 atoms and 10 atoms.

4. The model of a two-dimensional antiferromagnetic tunnel junction of claim 1, wherein: The thickness of the single layer FGT in step 3) is between The thickness of the single layer CIPS is between between 0.1 and 0.

5.

5. The model of a two-dimensional antiferromagnetic tunnel junction of claim 1, wherein, Step 4) the supercell expansion and stacking of the two-dimensional antiferromagnetic tunnel junction is: constructing 3x3 supercell of the single layer FGT and 2x2 supercell of the single layer CIPS, and then performing supercell expansion and stacking; wherein the initial distance between the single layer FGT and the single layer CIPS is set to be between 0.5a and 1.5a, and the length of the vacuum layer added in the Z direction, i.e. perpendicular to the sheet direction, is between 0.5a and 1.5a. When the single layer CIPS is in the ferroelectric state, the tunnel junction constructed with the single layer FGT has a stacking structure of 148 atoms in total; and when the single layer CIPS is in the antiferromagnetic state, the tunnel junction constructed with the single layer FGT will first change the two systems from hexagonal crystal system to orthorhombic crystal system, and then perform the supercell expansion and stacking to form a stacking structure of 296 atoms in total.​ 6. The model of a two-dimensional antiferromagnetic tunnel junction of claim 1, wherein, The RA is expressed as: where A is the unit cell area, T(ε F ) is the transmission function at the Fermi level, The TMR and TER are obtained from the following equations, respectively: TMR = |G P - G AP | / min(G P , G AP ) TER = |G FE - G AFE | / min(G FE , G AFE ) where G P and G AP are the conductivities of FGT with parallel and antiparallel magnetic order, respectively; G FE and G AFE are the conductivities of CIPS in ferroelectric and antiferroelectric states, respectively.

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