Two-dimensional FeTe2 and predicted Janus FeXS (X: Te and Se) monolayers with intrinsic half-metallic character: tunable electronic and magnetic properties via strain and electric field

monolayer tunes the bandgap of the spin-down channel in the half-metal phase. By contrast, for FeTeS, the biaxial strain transforms the ferromagnetic metal into a half-metal. The electric field applied to the FeSeS monolayer in a parallel direction transforms the half-metal to a ferromagnetic metal by closing the gap in the spin-down channel.