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CN-122021074-A - Design method of multiferroic body based on vanadium-doped two-dimensional ferroelectric body and multiferroic body

CN122021074ACN 122021074 ACN122021074 ACN 122021074ACN-122021074-A

Abstract

The invention belongs to the technical field of multiferroic materials, and relates to a design method of a multiferroic body based on vanadium doped two-dimensional ferroelectric body and the multiferroic body, wherein supercells with different sizes are obtained by expanding single-layer NbOI 2 unit cells in different directions, doping is carried out on the supercells with different sizes by taking vanadium as doping element to obtain doping configuration of each supercell under different doping concentrations, the doping configuration with the lowest total energy of ferromagnetic state and antiferromagnetic state under each doping concentration is used as a ground state configuration of the doping concentration, band gap Eg of the ground state configuration with different doping concentrations and spontaneous ferroelectric polarization intensity along a b axis are calculated, a double Y-axis graph is drawn by taking the doping concentration as an abscissa, the spontaneous ferroelectric polarization intensity and the band gap Eg as an ordinate, and a multiferroic phase region and a magnetic semispherical phase region are divided to obtain a doping concentration-evolution phase diagram, so that a doping concentration range corresponding to the ground state configuration with ferroelectricity and antiferromagnetic multiferroic phase is obtained.

Inventors

  • Hua Xinyue
  • QIAN TIANXIANG
  • ZHOU JU
  • CAI TIANYI

Assignees

  • 苏州大学

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. A method for designing a multiferroic body based on a vanadium-doped two-dimensional ferroelectric body, comprising: Obtaining a monolayer NbOI 2 as a primordial cell, and expanding the primordial cell in different directions to obtain supercells with different sizes; doping supercells with different sizes by taking vanadium as doping element to obtain doping configuration of each supercell under different doping concentrations; calculating the total energy of the ferromagnetic state and the antiferromagnetic state of each doping configuration under each doping concentration, and taking the doping configuration with the lowest total energy of the ferromagnetic state and the antiferromagnetic state under each doping concentration as the ground state configuration of the doping concentration; Calculating band gaps Eg of ground state configurations with different doping concentrations, spontaneous ferroelectric polarization intensity along a b axis, drawing a double Y-axis graph by taking the doping concentrations as abscissa and the spontaneous ferroelectric polarization intensity and the band gaps Eg as ordinate; And obtaining a doping concentration value range corresponding to the multi-iron phase with the ground state configuration having ferroelectricity and antiferromagnetic properties based on the doping concentration-physical evolution phase diagram, thereby designing and obtaining the multi-iron body.
  2. 2. The method for designing a multiferroic body based on a vanadium-doped two-dimensional ferroelectric body according to claim 1, wherein the method for designing the multiferroic body based on the vanadium-doped two-dimensional ferroelectric body is characterized by obtaining a monolayer NbOI 2 as a primitive cell, expanding the primitive cell in different directions to obtain supercells with different sizes, doping the supercells with different sizes by taking vanadium as a doping element to obtain doping configurations of the supercells under different doping concentrations, and comprises the following steps: Expanding along the lattice a axis of the primitive cell to obtain a supercell with a first size, expanding along the lattice b axis of the primitive cell to obtain a supercell with a second size, and simultaneously expanding along the lattice a axis and the lattice b axis of the primitive cell to obtain a supercell with a third size; And obtaining a plurality of doping concentrations distributed at equal intervals, and substituting Nb atoms with vanadium atoms in supercells with different sizes by taking each doping concentration as a target to obtain doping configurations corresponding to the supercells with different sizes under the doping concentration.
  3. 3. The method for designing a multiferroic body based on a vanadium doped two-dimensional ferroelectric according to claim 1, wherein calculating the total energy of the ferromagnetic state and the antiferromagnetic state for each doping configuration at each doping concentration comprises: carrying out structural relaxation on each doping configuration under each doping concentration to obtain a stable configuration of the doping configuration; And carrying out static self-consistent calculation on the steady-state configuration of the doping configuration to obtain the total energy of the ferromagnetic state and the antiferromagnetic state of the doping configuration.
  4. 4. A method of designing a multiferroic body based on a vanadium doped two-dimensional ferroelectric according to claim 3, wherein the structural relaxation of each doping configuration at each doping concentration results in a stable configuration of the doping configuration, comprising: inputting a crystal structure file, a parameter control file, a k-point grid file, a pseudo potential file and an operation control file of each doping configuration under each doping concentration into a magnetic state calculation catalog; setting the maximum iteration step number of the ion steps in the parameter control file to be 30, and then starting VASP relaxation calculation; And when the ion step is iterated until the maximum stress of the atoms is less than 0.01 eV/A, ending the relaxation, and generating a stable configuration file of the doping configuration.
  5. 5. The method for designing a multiferroic body based on a vanadium-doped two-dimensional ferroelectric according to claim 4, wherein the static self-consistent calculation is performed on the steady-state configuration of the doping configuration to obtain the total energy of the ferromagnetic state and the antiferromagnetic state of the doping configuration, comprising: taking a stable configuration file of a doping configuration as a crystal structure file of the doping configuration, setting the maximum iteration step number of the ion steps in a parameter control file to be 0, and then starting self-consistent calculation; and obtaining the total energy of the ferromagnetic state and the antiferromagnetic state of the doping configuration based on the 1F energy value in the output file after the self-consistent calculation is finished.
  6. 6. The method for designing a multiferroic body based on a vanadium-doped two-dimensional ferroelectric body according to claim 1, wherein calculating the band gap Eg of ground state configuration of different doping concentrations, the spontaneous ferroelectric polarization along the b-axis, comprises: Taking a central symmetry phase corresponding to each ground state configuration as a reference phase, and acquiring a plurality of intermediate transition phase types corresponding to the atomic displacement changing from 100% to 10% based on the reference phase; performing structural relaxation and self-consistent calculation on each intermediate transition phase type to obtain a polarization displacement related value of each intermediate transition phase type and a polarization displacement reference value of a reference phase; Calculating the spontaneous ferroelectric polarization intensity of each intermediate transition phase type along the b axis based on the polarization displacement related value of each intermediate transition phase type, the polarization displacement reference value of the reference phase and the lattice parameters of the ground state configuration along the a axis and the b axis, so as to obtain the spontaneous ferroelectric polarization intensity of the ground state configuration along the b axis; Carrying out structural relaxation and self-consistent calculation on each ground state configuration to obtain a stable configuration; And performing spin polarization energy band calculation based on the crystal structure file, the parameter control file, the k-point grid file, the pseudo-potential file, the operation control file and the stable configuration file of the ground state configuration to obtain energy band data of the ground state configuration, so that the band gap Eg of the ground state configuration is calculated based on the energy band data.
  7. 7. The method for designing a multiferroic body based on a vanadium-doped two-dimensional ferroelectric according to claim 1, wherein the steps of dividing a multiferroic phase region and a magnetic half-metal phase region in a double-Y-axis graph to obtain a doping concentration-physical evolution phase diagram comprise dividing the double-Y-axis graph into the multiferroic phase region and the magnetic half-metal phase region based on the fact that a band gap Eg of the multiferroic phase region is larger than a preset threshold value and a band gap Eg of the magnetic half-metal phase region is smaller than the preset threshold value, wherein the preset threshold value is smaller than or equal to 0.01eV.
  8. 8. The method for designing a multiferroic body based on a vanadium-doped two-dimensional ferroelectric body according to claim 1, wherein the range of doping concentration corresponding to the case of a multiferroic phase having ferroelectricity and antiferromagnetic properties in a ground state configuration is [0.125,0.625]; the corresponding doping concentration range is [0.75,0.875] when the ground state configuration is the half metal phase; when the doping concentration is 1, the ground state configuration is a ferromagnetic metal phase.
  9. 9. The method for designing a multiferroic body based on a vanadium-doped two-dimensional ferroelectric according to claim 1, wherein the designing of the multiferroic body based on the range of the doping concentration values comprises: Based on the doping concentration range, equivalent cation doping is carried out by utilizing vanadium ion pair NbOI 2 , so that the atom dimerization structure of NbOI 2 is destroyed, and the local magnetic moment is activated, so that the multiferroic body is prepared.
  10. 10. A multiferroic body, characterized in that it is designed by the design method of a multiferroic body based on a vanadium-doped two-dimensional ferroelectric body according to any one of claims 1 to 9.

Description

Design method of multiferroic body based on vanadium-doped two-dimensional ferroelectric body and multiferroic body Technical Field The invention relates to the technical field of multiferroic materials, in particular to a design method of a multiferroic body based on vanadium-doped two-dimensional ferroelectric body and the multiferroic body. Background In recent years, the two-dimensional multiferroic material has great application potential in the fields of next-generation spin electronic devices, magnetoelectric sensors, polymorphic storage and the like by virtue of the unique properties of atomic-level thickness, coexistence of ferroelectric sequences and magnetic sequences and the like. However, the development thereof faces a fundamental challenge in that ferroelectricity and magnetism have inherent conflict in electronic structure, and ferroelectricity generally requires cations to beConfiguration, while magnetism depends on the partially filled d-track (e.gN +.0), which makes intrinsic two-dimensional multiferroic materials extremely rare. In order to solve the problems, the current research mainly focuses on introducing magnetism into a non-magnetic two-dimensional system and realizing coexistence and coupling of the magnetism and the magnetism through external fields or structural engineering means such as doping, heterojunction construction and strain regulation, for example, multiferroic performance of the non-magnetic two-dimensional system is optimized in a BiFeO 3 -based nanomaterial, a magneto-electric coupling mechanism is explored in a system such as a FeI 2/In2Se3 heterojunction and strain regulation ZnIn 2S4, and a magnetic superlattice is constructed through an intercalation-cation exchange strategy, which shows that through reasonable material design and physical regulation, collaborative design and functional integration of ferroelectric, magnetic and magneto-electric coupling can be realized under two-dimensional limits, and a rich material platform and physical foundation are provided for a novel low-power consumption and high-integration information device. Specifically, monolayer NbOI 2 is a two-dimensional material in NbOX 2 family with robust room temperature ferroelectricity, which, from a microscopic perspective, originates from the synergistic effect of Nb 4+ ionic electron configuration and crystal structure distortion, namely the 4d 1 electron half-occupation of NbThe orbitals, as shown in (a) and (b) of FIG. 1, form Nb-Nb dimerized structures along the a-axis while along the b-axisThe track remains empty, simulating in electronic structureConfiguration, meeting ferroelectricity requirements, dimerization of a-axis results in adjacentThe orbitals overlap to form localized electron pairs, quenching the magnetic moment, rendering the system nonmagnetic. In order to solve the problem that intrinsic multiferroics are difficult to realize due to mutual repulsion of ferroelectricity and magnetic electrons In the two-dimensional ferroelectric material, the main strategies In the prior art include building van der Waals heterojunction, applying epitaxial strain and the like, for example, building heterojunction through stacking FeI 2 and In 2Se3, inducing magneto-electric coupling at an interface, or regulating the flat band structure of ZnIn 2S4 by utilizing biaxial tensile strain so as to excite the cruising ferromagnetism, however, the problems of complex process, unstable interface, weak coupling strength or difficult integration exist In the method, the problems of fundamental conflict between ferroelectricity and the magnetic electronic structure cannot be solved, the intrinsic multiferroics are still difficult to be shown by the materials, in addition, the method of applying epitaxial strain can regulate the electronic structure and the magnetic sequence of the material, but an external loading device is generally needed In a practical device, static, uniform and integratable continuous strain is difficult to be realized, excessive strain can cause lattice distortion and even fracture, and especially, the tiny structural disturbance can destroy the ferroelectricity origin and inhibit functional performance of NbOI 2 single layers with fine structural characteristics such as Peierls dimerization. In summary, the existing design method of the two-dimensional multiferroic material has the problems of complex process, unstable interface, weak coupling strength, difficult integration, incapability of enabling the material to show intrinsic multiferroic property, and even damage to the material structure. Disclosure of Invention Therefore, the technical problem to be solved by the invention is to solve the problems that the design method of the two-dimensional multiferroic material in the prior art has complex process, unstable interface, weak coupling strength, difficult integration, incapability of enabling the material to show intrinsic multiferroic property and even damage to