Magnetic and transport properties of two-dimensional ferromagnet VSe2 with Se vacancies

As a room-temperature van der Waals intrinsic ferromagnetic semiconductor, monolayer VSe2 was studied extensively for both fundamental research and potential low-dimensional semiconductor spintronic applications. Defects are inevitably encountered and can affect the electronic, magnetic, and transport properties during the experimental synthesis of VSe2 monolayer. However, the study of defects in VSe2 monolayer is still lacking at the atomic level. Here, the electronic, magnetic, and transport properties of VSe2 monolayer with Se vacancies are investigated by first-principles density-functional method. With the direction of easy magnetization axes unchanged, introducing Se vacancies results in the decrease of magnetic anisotropy energy and Curie temperature, which can be further increased by applying in-plane biaxial strain. After Se vacancies are introduced, the conductivity of the system decreases, while the larger doping range is obtained for pure spin-polarized current. The transition from semiconductor to half-metal with 100% spin polarization can be realized by introducing Se bivacancy in VSe2 monolayer, which is highly promising for next-generation spin filter, spin injection and spin transport nanodevices. PACS: 61.72.jd; 73.20.At; 75.50.Pp; 75.70.Ak