  The structural, electronic, and magnetic properties of VSSe, VSeTe, 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.
