A three-layer heterostructure of transition metal sulfides

Abstract

The present application relates to a kind of three-layer transition metal sulfide heterostructure and preparation method, two layers of identical two-dimensional transition metal sulfide are placed in the outermost two layers, a different two-dimensional transition metal sulfide is placed in the middle, and the outermost two layers of two-dimensional transition metal sulfide are rotated θ / 2 and-θ / 2 relative to the two-dimensional transition metal sulfide of middle layer respectively, so that the outermost two layers of two-dimensional transition metal sulfide are relatively rotated θ, form mirror face twist symmetry M 01 X2 / M 02 X2 / M 01 X2 Three-layer corner TMD heterostructure;The electron and hole layer separation of interlayer exciton of the heterostructure makes the optical dipole moment almost disappear, thereby increasing the lifetime of topological exciton, solving the conflict between topological structure and long lifetime;The mirror face twist symmetry of the heterostructure provides a high-efficiency boson continuum medium model for interlayer moiré exciton, and can realize quadrupole exciton with mirror face symmetry and dipole exciton with opposite dipole moment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum moire superlattice, and particularly relates to a three-layer transition metal sulfide heterostructure. BACKGROUND

[0002] Two-dimensional transition metal sulfide (TMD) based semiconductors have become a platform for realizing strong correlated electrons and topological nontriviality due to their narrow bandwidth and interwound electron wave function characteristics. In TMD superlattices with nontrivial band topology, many strong correlated electron phenomena such as Mott insulator and generalized Wigner crystal have been observed in experimental studies. In TMD superlattices with topological bands, relevant phases with topological nontriviality such as integer quantum anomalous Hall state and fractional quantum anomalous Hall state have been observed in experimental studies. The above experimental study observations show that TMD moire superlattice is a real material platform for realizing fermionic quantum simulation.

[0003] The periodic characteristics of TMD superlattices enable excitons to obtain specific Chern numbers in an effective valley Zeeman field. At present, inhomogeneous bilayer TMD moire superlattices, the incompressible correlated state of excitons and the Bose Mott insulator have been observed, which opens up a new research field for studying the many-body state of bosons. In these superlattices, the modulation effect of moire stripes leads to a significant on-site energy of excitons on a triangular lattice, effectively simulating the Bose-Hubbard model. For example, a research team found excitons with strong Hubbard interaction in a WSe / WS bilayer moire superlattice, which occupy the same moire lattice site and exhibit a correlated bosonic state similar to the Mott insulating state of electrons.

[0004] However, in a bilayer moire superlattice, the larger optical dipole moment of in-plane excitons leads to a shorter exciton lifetime. Therefore, a third layer of MoSe2 is added to a corner homojunction tWSe2 to form a WSe2 / WSe2 / MoSe2 three-layer TMD model to form an interlayer exciton with a longer lifetime than an in-plane exciton, but the WSe2 / WSe2 / MoSe2 three-layer TMD model is not conducive to constructing a continuous model Hamiltonian. SUMMARY

[0005] Based on this, the purpose of the present application is to provide a three-layer transition metal sulfide heterostructure.

[0006] A three-layer transition metal sulfide heterostructure comprises:

[0007] a first two-dimensional transition metal sulfide layer M 01X2, a second two-dimensional transition metal sulfide layer M 02 X2and a third two-dimensional transition metal sulfide layer M 03 X2, a first two-dimensional transition metal sulfide layer M 01 X2relative to the second two-dimensional transition metal sulfide layer M 02 X2is rotated by θ / 2, a third two-dimensional transition metal sulfide layer M 03 X2relative to the second two-dimensional transition metal sulfide layer M 02 X2is rotated by -θ / 2, and a first two-dimensional transition metal sulfide layer M 01 X2and a third two-dimensional transition metal sulfide layer M 03 X2is the same.

[0008] Further, the first two-dimensional transition metal sulfide layer M 01 X2relative to the third two-dimensional transition metal sulfide layer M 03 X2is rotated by θ, forming a mirror-twinned symmetric M 01 X2 / M 02 X2 / M 03 X2is a two-dimensional transition metal sulfide.

[0009] Further, the first two-dimensional transition metal sulfide layer M 01 X2, a second two-dimensional transition metal sulfide layer M 02 X2and a third two-dimensional transition metal sulfide layer M 03 X2are both monolayers.

[0010] Further, the second two-dimensional transition metal sulfide layer M 02 X2and a first two-dimensional transition metal sulfide layer M 01 X2, a third two-dimensional transition metal sulfide layer M 03 X2are all different.

[0011] Further, the θ is 0.9° to 1.9°.

[0012] Further, M 01 , M 02 , M 03 is one of Ti, In, Ta, Mo, W, Re, M 01 , M 03 is different from M 02 .

[0013] Further, X is S or Se.

[0014] Further, the first two-dimensional transition metal sulfide layer M 01 X2, a third two-dimensional transition metal sulfide layer M 03 X2is WSe2; a second two-dimensional transition metal sulfide layer M02 X2 is MoSe2.

[0015] Compared with the prior art, the three-layer corner transition metal sulfide heterostructure provided by the application is formed by placing two layers of the same two-dimensional transition metal sulfide at the outermost two layers, placing a different two-dimensional transition metal sulfide in the middle, and rotating the two outermost two-dimensional transition metal sulfides by θ / 2 and -θ / 2, respectively, relative to the two-dimensional transition metal sulfide in the middle, so that the two outermost two-dimensional transition metal sulfides are relatively rotated by θ, to form a mirror twist symmetric M 01 X2 / M 02 X2 / M 01 The three-layer corner TMD heterostructure of X2; the electron and hole layer separation of the interlayer exciton of the heterostructure makes the optical dipole moment almost disappear, thereby increasing the lifetime of the topological exciton, and solving the conflict between the topological structure and the long lifetime; the mirror twist symmetry of the heterostructure ensures that the moire potential generated by the moire superlattice can be treated by harmonic approximation, thereby providing a high-efficiency bosonic continuous medium model for the interlayer moire exciton, that is, a continuous topological exciton band is obtained, and a mirror symmetric quadrupole exciton and a dipole exciton with opposite dipole moments can be realized. The long-lifetime exciton is beneficial to many application fields, especially the efficiency and stability of optoelectronic devices, directly affecting the development of new materials, the reliability of quantum information, and the performance improvement of optoelectronic systems.

[0016] Meanwhile, the application provides a preparation method of the three-layer transition metal sulfide heterostructure, characterized by comprising the following steps:

[0017] S10, a polymethyl methacrylate (PPC) film is attached to the center of a polydimethylsiloxane (PDMS) cushion on a glass slide to obtain a PDMS / PPC layer;

[0018] S20, a single-layer M 01 X2, a single-layer M 03 X2, and a single-layer M 02 X2 is placed in the center of a sample displacement stage of a microscope;

[0019] S30, the PDMS / PPC layer on the glass slide is mounted to a cantilever of the microscope, and the height of the microscope and the sample displacement stage are adjusted, so that the single-layer M 01 X2 is found in the ocular lens, the cantilever is adjusted so that the lowest point of the PDMS / PPC layer is aligned with the single-layer M 01 X2, and the microscope is slowly lowered until color Newton rings appear; the heating stage is controlled to heat, and the attachment of the PDMS / PPC and the single-layer M 01 X2 is observed by a CCD to obtain a PDMS / PPC / M 01 X2 layer;

[0020] S40, the cantilever is adjusted so that the PDMS / PPC / M01 X2 layer aligns with single layer M 02 X2, slowly lower until the color Newton ring appears; control the heating table heating, and adjust the platform rotation angle control PDMS / PPC / M 01 X2 layer aligns with single layer M 02 X2 stack corner, observe PDMS / PPC / M by CCD 01 X2 layer aligns with single layer M 02 X2 fit, make PDMS / PPC / M 01 X2 / M 02 X2 layer;

[0021] S50 adjust the cantilever to make PDMS / PPC / M 01 X2 / M 02 X2 layer aligns with single layer M 03 X2, slowly lower until the color Newton ring appears; control the heating table heating, and adjust the platform rotation angle control PDMS / PPC / M 01 X2 / M 02 X2 layer aligns with single layer M 03 X2 stack corner, observe PDMS / PPC / M by CCD 01 X2 / M 02 X2 layer aligns with single layer M 03 X2 fit, make PDMS / PPC / M 01 X2 / M 02 X2 / M 03 X2 layer;

[0022] S60 adjust the cantilever to move along the positive half axis direction of Z axis, remove the PDMS / PPC layer on the glass slide; remove M 01 X2 / M 02 X2 / M 03 X2 layer residual PPC removal, make three layers M 01 X2 / M 02 X2 / M 03 X2 heterojunction trench.

[0023] In order to better understand and implement the present application, the present application is described in detail below in conjunction with the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of the heterostructure of WSe2 / MoSe2 / / WSe2 for an embodiment of the present application;

[0025] Figure 2 is a schematic diagram of the exciton formation; Figure 1

[0026] Figure 3 ​Schematic diagram of the exciton moiré band structure at a rotation angle of 1°;

[0027] Figure 4 Bellic curvature diagram of the lowest exciton band when the filling number is -1;

[0028] Figure 5 Real space distribution diagram of the bottom component of Wannier A;

[0029] Figure 6 Real space distribution diagram of the top component of Wannier A;

[0030] Figure 7 Real space distribution diagram of the bottom component of Wannier B;

[0031] Figure 8 Real space distribution diagram of the top component of Wannier B;

[0032] Figure 9 Real space distribution diagram of the bottom component of Wannier O;

[0033] Figure 10 Real space distribution diagram of the top component of Wannier O;

[0034] Figure 11 Ground state diagram of A, B and O sites when the filling number is 1 / 3;

[0035] Figure 12 Ground state diagram of A, B and O sites when the filling number is 1. DETAILED DESCRIPTION

[0036] See Figure 1 and Figure 2 The three-layer transition metal sulfide heterostructure described in the present application comprises a first two-dimensional transition metal sulfide layer M 01 X2, a second two-dimensional transition metal sulfide layer M 02 X2and a third two-dimensional transition metal sulfide layer M 03 X2, wherein the first two-dimensional transition metal sulfide layer M 01 X2is rotated by θ / 2 relative to the second two-dimensional transition metal sulfide layer M 02 X2, the third two-dimensional transition metal sulfide layer M 03 X2is rotated by -θ / 2 relative to the second two-dimensional transition metal sulfide layer M 02 X2, the first two-dimensional transition metal sulfide layer M 01 X2is rotated by θ relative to the third two-dimensional transition metal sulfide layer M 03 X2, forming a mirror-symmetrically twisted M 01 X2 / M 02 X2 / M03 Two-dimensional transition metal sulfides of X2.

[0037] Among them, the first two-dimensional transition metal sulfide layer M 01 X2, the second two-dimensional transition metal sulfide layer M 02 X2 and the third two-dimensional transition metal sulfide layer M 03 X2 are all single layers; the first two-dimensional transition metal sulfide layer M 01 X2 and the third two-dimensional transition metal sulfide layer M 03 Same as X2, second two-dimensional transition metal sulfide layer M 02 X2 and the first two-dimensional transition metal sulfide layer M 01 X2 and the third two-dimensional transition metal sulfide layer M 03 X2 is different.

[0038] Among them, M 01 M 02 M 03 It is one of Ti, In, Ta, Mo, W, and Re, and M 01 and M 03 Same, M 01 M 03 With M 02 They are not the same; X is either S or Se.

[0039] Meanwhile, θ is set to 0.9°~1.9°.

[0040] Meanwhile, this invention proposes a method for preparing the heterostructure of the three-layer transition metal sulfide, including the following steps.

[0041] S10 involves attaching a polymethyl methacrylate (PPC) film to the center of a polydimethylsiloxane (PDMS) pad on a glass slide to obtain a PDMS / PPC layer.

[0042] S20 will be a single layer M 01 X2, Single-layer M 03 X2 and single-layer M 02 Place X2 at the center of the sample displacement stage of the microscope.

[0043] S30: Mount the PDMS / PPC layer from the slide onto the microscope cantilever, and adjust the microscope height and sample stage. Locate the monolayer M in the eyepiece. 01 X2, Adjust the cantilever to align the lowest point of the PDMS / PPC layer with the single-layer M 01 X2, slowly descend until colored Newton's rings appear; control the heating stage to heat, and observe the PDMS / PPC and single-layer M through CCD. 01 X2 bonding produces PDMS / PPC / M 01 X2 layer.

[0044] S40 adjust the cantilever to make PDMS / PPC / M 01 X2 layer aligns with monolayer M 02 X2, slowly lower until color Newton ring appears; control heating stage to heat, and adjust platform rotation angle to control PDMS / PPC / M 01 X2 layer and monolayer M 02 X2 stack corner, observe PDMS / PPC / M by CCD 01 X2 layer and monolayer M 02 X2 fit, make PDMS / PPC / M 01 X2 / M 02 X2 layer.

[0045] S50 adjust the cantilever to make PDMS / PPC / M 01 X2 / M 02 X2 layer aligns with monolayer M 03 X2, slowly lower until color Newton ring appears; control heating stage to heat, and adjust platform rotation angle to control PDMS / PPC / M 01 X2 / M 02 X2 layer and monolayer M 03 X2 stack corner, observe PDMS / PPC / M by CCD 01 X2 / M 02 X2 layer and monolayer M 03 X2 fit, make PDMS / PPC / M 01 X2 / M 02 X2 / M 03 X2 layer.

[0046] S60 adjust the cantilever to move along the positive half-axis direction of Z axis, remove PDMS / PPC layer on the glass slide; remove M 01 X2 / M 02 X2 / M 03 X2 layer residual PPC is removed, and a three-layer M is prepared 01 X2 / M 02 X2 / M 03 X2 heterojunction trench.

[0047] In specific implementation, the first two-dimensional transition metal sulfide layer M 01 X2, the third two-dimensional transition metal sulfide layer M 03 X2 is WSe2, the second two-dimensional transition metal sulfide layer M 02 X2 is MoSe2, a three-layer corner TMD heterostructure of WSe2 / MoSe2 / WSe2 is formed, and the preparation method is as follows:

[0048] S10 The PMMA film is taken from the silicon wafer with the help of the adhesive tape with small holes, and the PMMA film is pasted in the center of the PDMS cushion of the glass slide to obtain the PDMS / PPC layer.

[0049] S20 The two monolayer WSe2 and monolayer MoSe2 are placed in the center of the sample displacement table of the microscope.

[0050] S30 The PDMS / PPC layer on the glass slide is placed on the cantilever of the microscope, and the height of the microscope and the sample displacement table are adjusted. The monolayer WSe2 area is found in the ocular lens. The lowest point of the PDMS / PPC layer is aligned with the monolayer WSe2 area. Slowly lower until the colored Newton ring appears. The temperature of the heating table is controlled to be 40℃. After reaching 40℃, heat for 10 min. The fit of the PDMS / PPC and the monolayer WSe2 is observed by the CCD to obtain the PDMS / PPC / WSe2 layer.

[0051] Further, the monolayer WSe2 area is located at the edge of the Newton ring.

[0052] S40 The lowest point of the PDMS / PPC / WSe2 layer is aligned with the monolayer MoSe2 area. Slowly lower until the colored Newton ring appears. The temperature of the heating table is controlled to be 10℃ as a superposition unit. In turn, increase to 110℃. After reaching 110℃, heat for 10 min. The stacking angle of the PDMS / PPC / WSe2 layer and the monolayer MoSe2 is controlled by adjusting the rotation angle of the platform. The fit of the PDMS / PPC / WSe2 layer and the monolayer MoSe2 is observed by the CCD to obtain the PDMS / PPC / WSe2 / MoSe2 layer.

[0053] S50 The lowest point of the PDMS / PPC / WSe2 / MoSe2 layer is aligned with the other monolayer WSe2 area. Slowly lower until the colored Newton ring appears. The temperature of the heating table is controlled to be 110℃. The stacking angle of the PDMS / PPC / WSe2 / MoSe2 layer and the monolayer WSe2 is controlled by adjusting the rotation angle of the platform. The fit of the PDMS / PPC / WSe2 / MoSe2 layer and the monolayer WSe2 is observed by the CCD to obtain the PDMS / PPC / WSe2 / MoSe2 / WSe2 layer.

[0054] S60 The cantilever is adjusted to move along the positive half-axis direction of the Z axis to remove the PDMS / PPC layer on the glass slide. The residual PPC of the WSe2 / MoSe2 / WSe2 layer is removed by annealing to obtain the three-layer WSe2 / MoSe2 / WSe2 heterojunction trench. The low pressure state is maintained during annealing. The gas is 300sccm Ar. The annealing temperature is 290℃. The time is 8h.

[0055] The physical mechanism of the present application is analyzed as follows.

[0056] (I) Obtain exciton topological energy band

[0057] Since the exciton binding energy (about 100 meV) is much larger than the moire potential and the interlayer hybridization potential (0-10 meV), the exciton in the moire superlattice is approximated, and the physical effect brought by the moire superlattice is ignored, and the Bethe-Salpeter equation (BXE) is solved.

[0058] The exciton state is described by the center-of-mass momentum, and the corresponding exciton wave function |X l (Q)> satisfies:

[0059]

[0060] In the formula: |0> is the vacuum state of the filled valence band electrons, A is the normalization coefficient, represents the generation of an electron in the conduction band of the +K valley of the MoSe2 layer, represents the generation of a hole in the valence band of the +K valley of the top WSe2 layer, τ = ±1 refers to the ±K valley, k is the electron-hole relative momentum, and Q is the center-of-mass momentum of the electron-hole, wherein, is the effective mass of the exciton, is the electron-hole relative motion wave function in momentum space, is normalized, l (Q)|X l (Q)> = 1.

[0061] |X l (Q)> is the exciton wave function of the top WSe2, and similarly, the exciton wave function |X2(Q)> of the bottom WSe2 satisfies:

[0062]

[0063] In the formula: represents the generation of a hole in the valence band of the +K valley of the bottom WSe2 layer.

[0064] The electron and hole in an exciton are bound by Coulomb interaction. In the parabolic band approximation, when the binding energy is small compared to the band gap, the parabolic approximation is accurate, and at this time, the electron-hole relative wave function is determined by the following formula:

[0065]

[0066] In the formula: and is the effective mass approximation of the single-layer conduction band dispersion and the valence band dispersion, E gwhere E is the band gap, S is the exciton band index, is the direct interlayer Coulomb interaction matrix, A is the normalization factor, ε = 3.8 is the effective dielectric constant, and d = 0.67 nm is the interlayer distance.

[0067] For MoSe2, For WSe2, With the above parameters, the BXE equation is solved, and the exciton energy E b,X = 161 meV.

[0068] According to the calculated exciton internal wave function is used to construct the exciton moiré Hamiltonian.

[0069] Considering the moiré potential of the moiré superlattice and the influence of interlayer hybridization, the Hamiltonian of the interlayer exciton continuous model is derived.

[0070] Since the valence band is in the tWSe2 superlattice, the hole component of the exciton will experience a moiré potential modulation, and the form of the moiré potential is:

[0071]

[0072] where: V and Φ are the amplitude and phase parameters of the moiré potential, s i,l = (-1) i+l-1 , and is the moiré reciprocal vector, is the counterclockwise rotation around the z-axis

[0073] By Fourier transforming U l (r) to the moiré potential, we obtain the moiré potential of the exciton:

[0074]

[0075] where: "+" indicates considering the +K valley, "-" reflects that the exciton experiences a moiré potential opposite to the valence electron, depends on the overlap of the exciton internal wave function and the relative displacement α c g1, and decreases with the increase of the twist angle.

[0076] Due to the real-space periodic interlayer hybridization between holes in the tWSe2 valence band, the X1 and X2 excitons are hybridized, resulting in non-trivial layer pseudo-spin winding. In the lowest-order harmonic approximation, the interlayer hybridization potential of the +K valley is represented as:

[0077]

[0078] where t is the interlayer tunneling strength, q1=K1-K2 is the momentum shift of K point in two layers of WSe2, which can be obtained by triple rotation from q1. The interlayer hybridization potential of +K valley can be obtained by projecting to the exciton vector,

[0079]

[0080] Combining the above equations, the full exciton moire Hamiltonian with the basis vectors of {|X1> + ,|X2> +} is obtained:

[0081]

[0082] See Figure 3 , the parameters used are (V,Φ)=(7.8meV,65.7°) and t=2meV. The Hamiltonian of this continuous model is expanded in plane waves and diagonalized, and the exciton moire band structure at a twist angle of 1° is obtained. The band structure has three narrow low-energy bands isolated from the high-energy bands.

[0083] See Figure 4 , the Berry curvature of the lowest band shows strong amplitude at the high-symmetry points γ and κ and band inversion occurs at the high-symmetry points. Due to the hybridization between X1 and X2 excitons, an energy gap is opened between the lowest two bands, and the Chern number combination of the two lowest bands is (-1,1), indicating the existence of a pair of time-reversal symmetry-protected bosonic spiral edge states in the gap.

[0084] (II) Construction of Wannier functions

[0085] Since the topological Chern number of the three lowest exciton moire bands is 0, the Wannier states are constructed from the three lowest exciton moire bands at θ=1°. The Wannier function (of the +K valley) at R=0 is represented as:

[0086]

[0087] where τ is the valley index, n is the three Wannier orbitals, N is the number of k points in the first Brillouin zone, is the Wannier state-related Bloch-like state, is the Bloch state of the nth moire band at k point, V kτ is the fixed gauge unitary matrix that maximally polarizes to the top layer and is real in real space,

[0088] ​Polarized to the lowest level and in real space For real numbers, In real space, O = (0,0)a M .

[0089] Please see Figures 5 to 8 Using the method described above, a Wannier function with θ = 1° was constructed, and W was plotted. A W B W O The top-level and bottom-level components of the three, W A and W B The dominance of the bottom and top components indicates that at sites A and B in real space, the interlayer excitons are dipole moment down and dipole moment up, respectively, and are transmitted through... The operation involves interconversion through lattice translation.

[0090] Please see Figure 9 , Figure 10 W O The presence of significant and equal weights on both layers indicates that the O site is provided by both the top and bottom layers. Each hole, with a tetrapole exciton composed of electrons in the middle layer, satisfies... symmetry.

[0091] (III) Constructing the TB Hamiltonian to compute quantum many-body phase diagrams

[0092] Based on the above results, a model consisting of W was constructed. A W B W o Effective Hamiltonian of the Bose tight-binding model of the orbital-formed honeycomb lattice:

[0093]

[0094] In the formula: It is acting on Boson production (annihilation) operators on functions, real space nearest neighbor vectors as well as Nearest neighbor vector Jump parameters E n″ (k) is the energy of the nth Mohr's band in the +K valley. and Together, they form the Kane-Mele model. The dispersion of the effective KM model is in very good agreement with the band structure of the continuous model, indicating that the TB Hamiltonian model has been successfully constructed.

[0095] Considering the same site R i The exciton interaction U, the in-situ energy, is given by the following equation:

[0096]

[0097] where α denotes the ABO three lattice sites,

[0098] The Coulomb interaction U between two sites R i and R j is given by

[0099]

[0100] where α and β denote the ABO three lattice sites, R i ≠ R j When α = β, the next nearest neighbor intra-species interaction is calculated, and When α ≠ β, the nearest neighbor inter-species interaction is calculated d represents the interlayer spacing, ε r represents the relative dielectric constant.

[0101] Based on the three-orbital model, the many-body Hamiltonian considering the Coulomb interaction of excitons can be expressed as:

[0102]

[0103] where: is the corresponding particle number operator, <i,j> represents the next nearest neighbor lattice site, and <<i,j>> represents the nearest neighbor lattice site.

[0104] The ground state of the three-layer corner TMD superlattice is calculated by the Bose Gutzwiller variational method to study the quantum many-body phase, and the variational ground state wave function can be expressed as follows:

[0105]

[0106] where α is the ABO three Wannier orbitals, N α is the total number of lattice sites related to W α , and the local wave function of W α at site i is is a variational parameter, and |n> iα represents the corresponding occupation number state.

[0107] The above variational wave function is brought into the many-body Hamiltonian to obtain the energy expression:

[0108]

[0109] In the minimization process, the global energy minimum is obtained with different initial states.

[0110] Referring to Figure 11 , the case of filling number is plotted, θ i = 0.9°, θ f = 1.9°, the order parameters φ iα = <b iα > of the three ABO lattice sites are all not zero, and the weak exciton interaction at the filling number leads to the superfluid characteristics.

[0111] Referring to Figure 12 , the case of filling number 1 is plotted, the order parameters φ iα = <b iα > of the three ABO lattice sites are all equal to 0, and the average particle number <n iα > is all equal to 1, and the ratio of the nearest-neighbor hopping parameter t to the on-site potential U in the small angle range is far less than 1, which leads to the Mott insulator characteristics of the three ABO lattice sites.

[0112] By comparing the two quantum many-body phase diagrams, it is obvious to note the strong physical effects caused by the difference in filling number.

[0113] The three-layer corner transition metal sulfide heterostructure provided by the application is formed by placing two layers of the same two-dimensional transition metal sulfide at the outermost two layers, placing a different two-dimensional transition metal sulfide in the middle, and rotating the two-dimensional transition metal sulfides in the outermost two layers by θ / 2 and -θ / 2 with respect to the two-dimensional transition metal sulfide in the middle layer, respectively, so that the two-dimensional transition metal sulfides in the outermost two layers are relatively rotated by θ, to form a mirror twist symmetric M 01 X2 / M 02 X2 / M 01 X2 three-layer corner TMD heterostructure; the electron and hole layer separation of the interlayer exciton of the heterostructure makes the optical dipole moment almost disappear, thereby increasing the lifetime of the topological exciton, and solving the conflict between the topological structure and the long lifetime; the mirror twist symmetry of the heterostructure ensures that the moire potential energy generated by the moire superlattice can be treated by harmonic approximation, thereby providing a high-efficiency bosonic continuum medium model for the interlayer moire exciton, that is, a continuous topological exciton band is obtained, and a dipole exciton with mirror symmetry and an opposite dipole moment can be realized. The long-lifetime exciton is beneficial to many application fields, especially the efficiency and stability of optoelectronic devices, directly affecting the development of new materials, the reliability of quantum information, and the performance improvement of optoelectronic systems.

[0114] In another aspect, the valley-projected exciton band structure of the three-layer corner transition metal dichalcogenide heterostructure has a set of rich bosonic topological bands with opposite Chern numbers of opposite valley pseudo-spins, indicating the existence of a pair of time-reversal symmetry-protected bosonic helical edge states in the energy gap. Due to the spin-momentum locking and topological nature of the bosonic helical edge states, they can be used for the development of quantum computing and information transmission technology and more stable electronic and information processing in nanoscale electronic devices.

[0115] The terminology used in the present application is merely for the purpose of describing particular embodiments and is not intended to limit the present application. In the present application and claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that "a plurality" and "several" mean two or more unless otherwise specified. "And / or" means and includes any or all possible combinations of one or more of the associated listed items. "First", "second", "third", etc. are only used to distinguish, not to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance. When the above description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. In the description of the present application, the specific meanings of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

[0116] The above-described embodiments only express some implementation manners of the present application, which are described in a more specific and detailed manner, but should not be understood as limiting the scope of the patent. It should be pointed out that, for those of ordinary skill in the art, some modifications and improvements can be made without departing from the concept of the present application, which are all within the scope of the present application.

Claims

1. A heterostructure of a three-layer transition metal sulfide, comprising: The first two-dimensional transition metal sulfide layer M stacked sequentially 01 X2, the second two-dimensional transition metal sulfide layer M 02 X2 and the third two-dimensional transition metal sulfide layer M 03 X2, characterized in that the first two-dimensional transition metal sulfide layer M 01 X2 relative to the second two-dimensional transition metal sulfide layer M 02 X2 rotated θ / 2, third two-dimensional transition metal sulfide layer M 03 X2 relative to the second two-dimensional transition metal sulfide layer M 02 X2 rotated by -θ / 2, making the first two-dimensional transition metal sulfide layer M 01 X2 relative to the third two-dimensional transition metal sulfide layer M 03 Rotating X2 by θ results in a mirror-symmetric M. 01 X2 / M 02 X2 / M 03 X2 is a two-dimensional transition metal sulfide, wherein θ is 0.9°~1.9°; and the first two-dimensional transition metal sulfide layer M 01 X2 and the third two-dimensional transition metal sulfide layer M 03 X2 is the same.

2. The heterostructure of the three-layer transition metal sulfide as described in claim 1, characterized in that, First two-dimensional transition metal sulfide layer M 01 X2, the second two-dimensional transition metal sulfide layer M 02 X2 and the third two-dimensional transition metal sulfide layer M 03 X2 are all single-layered.

3. The heterostructure of the three-layer transition metal sulfide as described in claim 1, characterized in that, Second two-dimensional transition metal sulfide layer M 02 X2 and the first two-dimensional transition metal sulfide layer M 01 X2, Third two-dimensional transition metal sulfide layer M 03 X2 are all different.

4. The heterostructure of the three-layer transition metal sulfide as described in claim 1, characterized in that, M 01 M 02 M 03 It is one of Ti, In, Ta, Mo, W, Re, M 01 M 03 With M 02 They are not the same.

5. The heterostructure of the three-layer transition metal sulfide as described in claim 4, characterized in that, X is either S or Se.

6. The heterostructure of the three-layer transition metal sulfide as described in claim 5, characterized in that, First two-dimensional transition metal sulfide layer M 01 X2, Third two-dimensional transition metal sulfide layer M 03 X2 is WSe2; the second two-dimensional transition metal sulfide layer M 02 X2 is MoSe2.

7. A method for preparing a heterostructure of a three-layer transition metal sulfide, characterized in that, Includes the following steps: S10: A polymethyl methacrylate (PPC) film is attached to the center of a polydimethylsiloxane (PDMS) pad on a glass slide to obtain a PDMS / PPC layer; S20: Single layer M 01 X2, Single-layer M 03 X2 and single-layer M 02 Place X2 at the center of the sample displacement stage of the microscope; S30: Mount the PDMS / PPC layer from the slide onto the microscope cantilever, and adjust the microscope height and sample stage. Locate the monolayer M in the eyepiece. 01 X2, Adjust the cantilever to align the lowest point of the PDMS / PPC layer with the single-layer M 01 X2, slowly descend until colored Newton's rings appear; control the heating stage to heat, and observe the PDMS / PPC and single-layer M through CCD. 01 X2 bonding produces PDMS / PPC / M 01 X2 layer; S40: Adjust the cantilever to allow PDMS / PPC / M 01 The lowest point of layer X2 is aligned with single layer M. 02 X2, slowly descend until the colored Newton's rings appear; control the heating stage to heat up, and adjust the platform rotation angle to control PDMS / PPC / M. 01 X2 layer and single layer M 02 The stacking corner of X2 was observed using a CCD on PDMS / PPC / M. 01 X2 layer and single layer M 02 X2 bonding to produce PDMS / PPC / M 01 X2 / M 02 X2 layer; S50: Adjust the cantilever to allow PDMS / PPC / M 01 X2 / M 02 The lowest point of layer X2 is aligned with single layer M. 03 X2, slowly descend until the colored Newton's rings appear; control the heating stage to heat up, and adjust the platform rotation angle to control PDMS / PPC / M. 01 X2 / M 02 X2 layer and single layer M 03 The stacking corner of X2 was observed using a CCD on PDMS / PPC / M. 01 X2 / M 02 X2 layer and single layer M 03 X2 bonding produces PDMS / PPC / M 01 X2 / M 02 X2 / M 03 X2 layer; S60: Adjust the cantilever to move along the positive Z-axis to remove the PDMS / PPC layer from the slide; remove the M layer by acetone soaking or annealing. 01 X2 / M 02 X2 / M 03 Residual PPC in layer X2 was removed to obtain a three-layer M 01 X2 / M 02 X2 / M 03 X2 heterojunction trench.

8. The method for preparing the heterostructure of the three-layer transition metal sulfide as described in claim 7, characterized in that, Residual PPC was removed by annealing. During annealing, a low-pressure state was maintained, and Ar gas with a flow rate of 300 sccm was introduced. The annealing temperature was 290℃ and the annealing time was 8 hours.

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