Study On The Electronic Properties Of Two-dimensional Dirac Materials

Due to the unique structure and electronic properties of the new two-dimensional(2D)material,it has a wide range of applications in spintronics devices and has also aroused great research enthusiasm among researchers.So far,two-dimensional materials include metals,semi-metals,semiconductors,insulators,and superconductor materials.The unique structure of these materials leads to unique electrochemical properties.The discovery of graphene has led the development trend of two-dimensional materials.Based on the first principles,this paper studies the structure and electronic properties of several new two-dimensional materials,analyzes the geometric structure and electronic properties of the materials to explore the quantum properties of the structure,and is mainly dedicated to finding new types of low energy consumption and ineffective Quality Dirac material.The research in this paper provides new alternative materials for the further development of two-dimensional Dirac materials,and provides a new direction for the preparation of new low-dissipation electron transport devices.First,we studied the two-dimensional CuP thin film material and found that it is a very stable and anisotropic Dirac material.Different from the isotropic Dirac cone,the anisotropic Dirac cone material has the characteristics of anisotropic carrier mobility,so that this type of material can be used in direction-dependent quantum devices.The characteristics of anisotropy have also attracted the interest of researchers.The CuP structure is a tetragonal lattice,and the Fermi velocity is of the same order of magnitude as that of graphene.However,the Fermi velocities from the Dirac point to the Y direction and the Dirac point to the?direction are different,which are 2.3×10⁵ m/s and 4.5×10⁵m/s,respectively.Through the calculation of Young's modulus and three-dimensional energy band,the results show that there is an anisotropic Dirac cone between Y-?in the single-layer CuP material.This is expected to be widely used in the preparation of spintronic devices related to orientation.Secondly,we studied the two-dimensional Dirac material W₂O₃ structure,which is also calculated based on first principles.The W₂O₃ monolayer has mechanical and thermodynamic stability at high temperatures.More importantly,we predicted a new single-spin Dirac Fermi state in the W₂O₃ monolayer.The biggest feature of this structure is the 100%spin polarizability.The Fermi speed is 3.48×10⁵ m/s.Considering the spin-orbit coupling,the Dirac cone near the Fermi surface will open a certain width of the band gap,and there is an edge state with symmetry protection,and the W₂O₃ film becomes a film that does not require additional doping with other elements.Quantum anomalous Hall effect insulator,namely QAH.Finally,in order to explore the source of the quantum anomalous Hall effect,we constructed a tight-binding model.These results show that the Kagome structure of W₂O₃ has great application prospects in the field of spintronic devices.Finally,we calculated a new hexagonal structure similar:Ni CS₃.Based on first-principles calculations,it is found that there are 12 fully spin-polarized Weyl points in a self-selected channel,and the Fermi velocity is also as high as 3.18×10⁵ m/s,which is almost comparable to graphene.Moreover,the two-dimensional material has good mechanical and thermodynamic stability,and the Curie temperature is estimated to reach 403 K.The Weyl point is protected by symmetry along the vertical mirror plane of?-K,and even under the influence of spin-orbit coupling after changing the spin direction,the band structure remains in a band-gap state.This property makes it possible to control the opening and closing of the Weyl point by adding external magnetic fields in different directions.This work not only provides a new type of two-dimensional Weyl semimetal material for the research field of symmetrically protected Weyl fermions,but also reveals the application mechanism of two-dimensional Weyl semimetal in spintronics.