Valley polarization and p-/n-type doping of monolayer WTe2 on top of Fe3O4(111)

The electronic properties of monolayer WTe2 on top of Fe3O4(111) are investigated by density functional theory. We find that the substrate termination of Fe3O4(111) can switch the conductivity of monolayer WTe2 from the p- to n-type. However, the stacking pattern can critically influence its electronic structure. For Fe(A)-terminated interfaces, stronger-bonding models show Fermi level pinning. Additionally, the time-reversal symmetry is broken by the proximity that leads to valley polarization. With particular stacking patterns, large valley splittings of 139, -76 and -72 meV are obtained for Fe(A)-, Fe(B)- and O-terminated models, respectively. Moreover, Fe(B)- and O-terminated ones have more applicable significance for valleytronics as no interference of the interface state appears at the valence band maximum. We demonstrate that proximity to a room-temperature ferromagnet is a convenient way to obtain valley polarization and adjust the conductivity of monolayer WTe2.