Two-dimensional magnetic semimetal material and theoretical calculation method thereof

Abstract

The application discloses the technical field of two-dimensional magnetic material performance regulation and control, and relates to a two-dimensional magnetic semimetal material and a theoretical calculation method thereof. The two-dimensional magnetic semimetal material has a sandwich layer structure composed of a first selenium atom layer, a vanadium atom layer and a second selenium atom layer inherent to a single-layer vanadium diselenide, and an oxygen atom layer formed by adsorbing oxygen atoms on the first selenium atom layer and / or the second selenium atom layer. The two-dimensional material has a semimetal characteristic and a spin polarization rate of 100% through calculation by a software package VASP. The application provides a basis for preparation of the two-dimensional magnetic semimetal material and has a wide prospect in miniaturization application of spintronic devices, and has important significance for device research and development in the post-moore era.

Description

Technical Field

[0001] This invention belongs to the field of performance regulation technology of two-dimensional magnetic materials, specifically relating to a two-dimensional magnetic half-metal material and its theoretical calculation method. Background Technology

[0002] Charge and spin are intrinsic properties of electrons. Current integrated circuits only utilize the degree of freedom of charge. Spintronics is achieved by utilizing and manipulating the spin and magnetic moment of electrons. Spintronic devices require semi-metallic materials with extremely high spin polarizability as electrodes to inject spin. In the early 1980s, deGroot et al. at the University of Nijmegen in the Netherlands discovered a new type of magnetic material, which they called a semi-metallic magnetic material, possessing a high conduction electron spin polarizability of up to 100%, showing broad application prospects in the field of spintronic devices. Chinese invention patent CN102129905A discloses a semi-metallic magnetic material V with high spin polarizability. x Co y N z M w Its spin polarization is between 90-100%, with actual measured values ​​between 80-96.2%, exhibiting extremely high material spin polarization. Chinese invention patent CN101550507B discloses a magnetic half-metal Heusler alloy material Co2Fe(Si). 1-x B x By adjusting the doping ratio of boron (B), the electronic structure can be controlled, enabling the material to simultaneously possess high spin polarization and high Curie temperature. This allows for high magnetoresistance when used in spin valves or magnetic tunnel junctions. However, both of these half-metallic magnetic materials are three-dimensional bulk structures, limiting their feasibility in the miniaturization of spintronic devices.

[0003] Two-dimensional materials, with a thickness of only one or a few atomic layers, can significantly reduce the size of integrated circuits. They possess excellent physical properties such as zero effective mass carriers, ultra-high mobility, and ultra-high optical absorption, making them promising for applications in optoelectronic devices, new energy batteries, and flexible wearable electronic devices. Reported two-dimensional materials include graphene, molybdenum disulfide, black phosphorus, blue phosphorus, VSe2, SnS, FeS, antimonyene, ZrTe5, silicene, germanene, stanene, MnSe2, CrI3, CrGeTe4, and borophene. Among these, graphene and silicene are non-magnetic half-metals, molybdenum disulfide, black phosphorus, and tin selenide are semiconductors, and chromium iodide is a magnetic semiconductor. No two-dimensional magnetic half-metals have been found among common two-dimensional materials.

[0004] Therefore, the development of two-dimensional magnetic semi-metallic materials is of great significance for the development of devices in the post-Moore era. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a two-dimensional magnetic semimetallic material and its theoretical calculation method. The specific solution is as follows:

[0006] The present invention provides a two-dimensional magnetic half-metal material having a sandwich layered structure consisting of a first selenium atom layer, a vanadium atom layer, and a second selenium atom layer inherent in a single layer of vanadium diselenide, and an oxygen atom layer formed by adsorbing oxygen atoms in the first selenium atom layer and / or the second selenium atom layer.

[0007] Furthermore, the spin polarization of the two-dimensional magnetic half-metal material is 100%.

[0008] This invention further provides a theoretical calculation method for two-dimensional magnetic half-metal materials, using the VASP software package to calculate the band structure of the two-dimensional magnetic half-metal material described in claim 1;

[0009] In the calculations, the exchange correlation energy of electrons is approximated using a PBE-type generalized gradient. The interaction between electrons and ions is described using the projected fused wave (PAW) method. To avoid interactions between adjacent cells, the vacuum layer in the Z direction is... The plane-wave basis set cutoff energy is 560 eV. K-point sampling in the Brillouin zone uses a Gamma-centered Monkhorst-Pack scheme, with a K-point grid of 17 × 17 × 1. The electronic relaxation precision is set to 10⁻⁶. -6 eV, the convergence criterion is that the force acting on each atom is less than eV.

[0010] The beneficial effects of this invention are as follows:

[0011] The two-dimensional magnetic half-metal material provided by this invention has a sandwich-like layered structure consisting of a first selenium atom layer, a vanadium atom layer, and a second selenium atom layer inherent to monolayer vanadium diselenide, as well as an oxygen atom layer formed by the adsorption of oxygen atoms in the first selenium atom layer and / or the second selenium atom layer. The aim is to modify the electronic structure of monolayer vanadium diselenide through the oxygen atom layer, thereby controlling its electrical and magnetic properties and endowing vanadium diselenide with half-metallic characteristics. Calculations using the VASP software package show that this two-dimensional material exhibits half-metallic characteristics with a spin polarization rate of 100%. This invention provides a basis for the preparation of two-dimensional magnetic half-metal materials, has broad prospects for miniaturization applications in spintronic devices, and is of great significance for the development of devices in the post-Moore's Law era. Attached Figure Description

[0012] Figure 1 This is a top view of the structure of VSe2O in Embodiment 1 of the present invention; wherein, 1-oxygen atom layer, 2-vanadium atom layer, 3-second selenium atom layer;

[0013] Figure 2 This is a side view of the structure of VSe2O in Embodiment 1 of the present invention; wherein, 1-oxygen atom layer, 2-vanadium atom layer, 3-second selenium atom layer, 4-first selenium atom layer;

[0014] Figure 3 This is the spin-up subband diagram of spin-polarized VSe2O in Embodiment 1 of the present invention;

[0015] Figure 4 This is the spin-down subband diagram of spin-polarized VSe2O in Embodiment 1 of the present invention;

[0016] Figure 5 This is the spin polarization state density distribution of VSe2O in Embodiment 1 of the present invention;

[0017] Figure 6 This is a top view of the structure of VSe2O2 in Embodiment 2 of the present invention; wherein, 1-oxygen atom layer, 2-vanadium atom layer, 3-second selenium atom layer, 4-oxygen atom layer;

[0018] Figure 7 This is a side view of the structure of VSe2O2 in Embodiment 2 of the present invention; wherein, 1-oxygen atom layer, 2-vanadium atom layer, 3-second selenium atom layer, 4-oxygen atom layer, 5-first selenium atom layer;

[0019] Figure 8 This is the spin-up subband diagram of spin-polarized VSe2O2 in Embodiment 2 of the present invention;

[0020] Figure 9 This is the spin-down subband diagram of spin-polarized VSe2O2 in Embodiment 2 of the present invention;

[0021] Figure 10 This is the spin polarization state density distribution of VSe2O2 in Example 2 of the present invention. Detailed Implementation

[0022] To provide a clearer understanding of the present invention, it is now further described with reference to the following embodiments and accompanying drawings. These embodiments are for illustrative purposes only and do not limit the invention in any way.

[0023] The theoretical calculations of the two-dimensional magnetic half-metal material in this invention were performed using the commercial computational software package VASP (Vienna Ab-initio Simulation Package) developed by the University of Vienna, Austria. VASP is a commonly used theoretical tool, developed based on density functional theory. During the calculations, the exchange correlation energy of electrons was approximated using the generalized gradient approximation (GGA) of the PBE (Perdew Burke Ernzerhof) type. The interaction between electrons and ions was described using the projected fused wave (PAW) method. To avoid interactions between adjacent cells, the vacuum layer in the Z direction was... The plane-wave basis set cutoff energy is 560 eV. K-point sampling in the Brillouin zone uses a Gamma-centered Monkhorst-Pack scheme, with a K-point grid of 17 × 17 × 1. The electronic relaxation precision is set to 10⁻⁶. -6 eV, the convergence criterion is that the force acting on each atom is less than eV. Using the VASP software package, the band structure and spin polarization state density distribution of the two-dimensional magnetic materials in Examples 1 and 2 were calculated.

[0024] Example 1

[0025] Two-dimensional semi-metallic magnetic VSe₂O consists of a single molecular layer of oxygen atoms adsorbed on the surface of a monolayer of VSe₂, with the structure as follows: Figure 1 and 2 As shown, the band structure is as follows Figure 3 and 4 As shown, the spin polarization state density distribution is as follows Figure 5 As shown, its spin-up band is in a semiconductor state, and the band gap is calculated to be 0.58 eV. Its spin-down band is in a metallic state, thus realizing a two-dimensional semi-metallic magnetic material with 100% spin polarization.

[0026] Example 2

[0027] Two-dimensional semi-metallic magnetic VSe₂O₂ consists of two molecular layers of oxygen atoms adsorbed on the surface of a monolayer VSe₂, with the structure as follows: Figure 6 and 7 As shown, the band structure is as follows Figure 8 and 9 As shown, the spin polarization state density distribution is as follows Figure 10 As shown, its spin-up band is in a semiconductor state, and the band gap is calculated to be 0.26 eV. Its spin-down band is in a metallic state, thus realizing a two-dimensional semi-metallic magnetic material with 100% spin polarization.

[0028] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A theoretical calculation method for two-dimensional magnetic half-metal materials, characterized in that, The band structure of the two-dimensional magnetic half-metal material was calculated using the VASP software package. The two-dimensional magnetic half-metal material has a sandwich-like layered structure consisting of a first selenium atom layer, a vanadium atom layer, and a second selenium atom layer inherent to a single layer of vanadium diselenide, as well as an oxygen atom layer formed by the adsorption of oxygen atoms in the first selenium atom layer and / or the second selenium atom layer. The spin polarization of the two-dimensional magnetic half-metal material is 100%.

2. The theoretical calculation method according to claim 1, characterized in that, During the calculation, the exchange correlation energy of electrons can be approximated by a PBE-type generalized gradient.

3. The theoretical calculation method according to claim 1, characterized in that, In the calculation process, the interaction between electrons and ions is described using the projected fused wave method.

4. The theoretical calculation method according to claim 1, characterized in that, In the calculation, the vacuum layer in the Z direction is 21 Å.

5. The theoretical calculation method according to claim 1, characterized in that, During the calculation, the cutoff energy of the plane wave basis set is 560 eV.

6. The theoretical calculation method according to claim 1, characterized in that, During the calculation, the K-point sampling of the Brillouin zone uses the Monkhorst-Pack scheme centered at Gamma, and the K-point grid is 17×17×1.

7. The theoretical calculation method according to claim 1, characterized in that, During the calculation, the electronic relaxation precision was set to 10. -6 eV, the convergence criterion is that the force acting on each atom is less than 0.01 eV / Å.

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