Bipolar magnetism in a two-dimensional NbS2 semiconductor with high Curie temperature

Abstract

Exploring two-dimensional (2D) crystals with intrinsic room-temperature magnetism is of particular importance to develop practical spintronics applications at the nanoscale. Here, we report the electronic and magnetic properties of a freestanding 2D NbS₂ crystal on the basis of first-principles calculations. Our results demonstrate that the 2D NbS₂ monolayer is a bipolar magnetic semiconductor with a spin bandgap of 0.27 eV by using the screened hybrid density functional HSE06 method. In particular, both electron and hole doping could induce the transition from a bipolar magnetic semiconductor to a half metal in NbS₂ nanosheets, where the spin-polarization direction of carriers in half-metallic NbS₂ nanosheets can be tuned with the doping type. The Monte Carlo simulation predicts a Curie temperature of over 141 K in the 2D NbS₂ crystal, which can be enhanced up to 273 K by hole doping or applying a biaxial tensile strain. These findings imply the great potential of 2D NbS₂ nanosheets in nanoscale spintronics applications.