Magnetic vanadium sulfide monolayers: transition from a semiconductor to a half metal by doping

Abstract

Two dimensional crystals, befitting nanoscale electronics and spintronics, can have versatile applications due to their ultrathin and flexible nature. We show by first-principles calculations that suitable doping can influence the exchange splitting of the spin and electronic states in VS₂ monolayers using the meta-GGA (MGGA) method by self-consistently introducing the exact-exchange interaction to the sub d shell of the V atoms. Among the large number of non-metallic atoms, H, B, C, N, P, As, O, Se, Te, F, Cl, and Br, As appears to be a candidate for p-type doping of the VS₂ monolayer with an appropriate formation energy. The enhancement of the conductivity is limited and the spin polarization of the As doped system is also slightly lowered from the mixed V-s state with an inverse spin orientation. H and halogen atoms (F, Cl, Br) are ideal candidates for n-type doping with very small and even negative formation energy. Particularly, a switch from a half semiconductor to a half metal is realized with enhanced conductivity and spin polarization in VS₂ monolayers from the increased magnetic moment of the nearest neighboring V atoms of the dopants under a rather wide range of doping density, which is very promising for spintronic applications.