Structural, electronic, and magnetic properties of vanadium-based Janus dichalcogenide monolayers: A first-principles study

The structural, electronic, and magnetic properties of VSSe, VSeTe, and VSTe monolayers in both 2H and 1T phases are investigated via first-principles calculations. The 2H phase is energetically favorable in VSSe and VSeTe, whereas the 1T phase is lower in energy in VSTe. For V-based Janus monolayers in the 2H phase, calculations of the magnetic anisotropy show an easy-plane for the magnetic moment. As such, they should not exhibit a ferromagnetic phase transition, but instead, a Berezinskii-Kosterlitz-Thouless (BKT) transition. A classical XY model with nearest-neighbor coupling estimates critical temperatures (T-BKT) ranging from 106 K for VSSe to 46 K for VSTe.