First-principles prediction of intrinsic piezoelectricity, spin-valley splitting and magneto-crystal anisotropy in 2H-VS2 magnetic semiconductor

The piezoelectricity, valley character and magnetic properties of intrinsic ferrovalley 2H-VS2 monolayer are studied using density functional theory. The results suggest that 2H-VS2 monolayer exhibits obvious bipolar magnetic semiconductor characters with Curie temperature (TC) of 278 K, large piezoelectric coefficient d11 of 3.925 pm/V, in-plane magneto-crystal anisotropy (MA) and large valley splitting (ΔKK′) of 75.1 meV. Applying in-plane strain (-6% to 6 %) can well adjust the ΔKK′ and TC from 72 meV to 76.7 meV and from 98 K to 397 K, respectively, resulting an obvious change of electronic structures from bipolar magnetic semiconductor to spin gapless semiconductor phase. The magnetic anisotropy energy (MAE) of 2H-VS2 monolayer firstly increases and then decreases as the strain increases from −6% to 6 %, which mainly originates from the contribution of V dx2-y2 and dxy orbitals. In addition, 2H-VS2 monolayer retains a large valley-contrasting Berry curvature and non-zero anomalous Hall conductivity, indicating that the transverse velocity of carriers is opposite to the effect of in-plane longitudinal electric field. These results suggest that the 2H-VS2 monolayer can become good candidates for the spintronic and valleytronic applications.