| With the increasing degree of digitalization and automation in society,the rapid rise of artificial intelligence represented by big data and big language models,the development of high performance integrated circuits is approaching the limit of Moore’s Law,while the development of commercial semiconductor devices has approached the physical limit of micro and nano processing.The use of electron spin freedom will become an important technical route to break through the current microelectronic technology bottle.Currently,the exploration of spintronic devices has triggered a new wave of research,and has become an important research direction in condensed matter physics and nanoelectronics,and considerable application results have been achieved.Since the successful stripping of single-layer graphite,two-dimensional materials have attracted rapid attention in the field of physics and materials science,and exhibit different electrical,optical and magnetic properties,which is expected to become an ideal candidate material for electronic devices in the future.However,intrinsic magnetic twodimensional materials are still relatively rare.The first discovered single-layer ferromagnetic two-dimensional materials,such as CrI3 and Cr2Ge2Te6,are all metal or semiconductor,and the Curie temperature is much lower than room temperature.The preparation conditions are harsh,which seriously limits the development of two-dimensional materials in spintronics applications.Therefore,it is very important to expand two-dimensional magnetic materials to realize their wider application in spintronics.As one of the transition metal disulfide compounds,vanadium disselenide(VSe2)has been proved to be a new two-dimensional material with many unique properties such as room temperature ferromagnetism,valley polarization,high conductivity and electrocatalysis.In 2020,Chua et al.experimentally observed a line defect structure of single-layer T-phase VSe2,that is,a quasi-one-dimensional arrangement eight-atom-ring line defect formed in single-layer T-phase VSe2 manufactured under the environmental condition of absence of Se.They suggest that the magnetism in VSe2 may be induced by this line defect,but the mechanism of the interaction between the defect and magnetism needs further investigation.Based on this.this paper combines density functional theory of first principles and non-equilibrium Green’s function method to carry out the following research on monolayer VSe2 with 8R line defect:First,the electronic structure and magnetic properties of intrinsic VSe2 and VSe2(8R-VSe2)with different density 8R line defects are studied.We found that the structure with the maximum linear defect density is semi-gold(spin-down band gap is 1.5 eV).With the decrease of linear defect density,the Coulomb interaction between defects weakens,and the spin-down conduction band decreases,which makes the energy band pass through Fermi level and change from semi-gold to gold,and the linear defect induces the local state.The magnetic moment of Se atom in VSe2 linear defect structure is enhanced compared with intrinsic VSe2.Second,this paper also selected 8R-VSe2 with different defect densities to design a doubleended device,and calculated its spin resolution transport properties,and compared with the intrinsic VSe2 device,it was found that the 8R-VSe2 device with the largest density defect in the bias range of±0.5 V has almost 100%spin filtration efficiency.The phenomenon of negative differential resistance occurs between 0.2 V～0.4 V(-0.4 V～-0.2 V)bias voltage.In view of these characteristics,the internal microphysical mechanism is further explained,and the possible practical application potential is expounded. |
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