Large valley polarization in monolayer MoTe₂ on a magnetic substrate

Abstract

On the basis of valley degree of freedom, there would be immense potential application in valleytronics. Introducing magnetism into triangular or hexagonal lattices is a promising route to realize valley polarization, which is indispensable for applying the valley degree of freedom. In this study, we explored valley polarization by depositing a heterostructure of a MoTe₂ monolayer on the (0 0 1) surface of an antiferromagnetic RbMnCl₃ substrate. First principles-calculations showed that due to proximity-induced Zeeman effects, the MoTe₂ monolayer was drastically magnetized by the topmost Mn layer in the substrate and a very large valley splitting (about 109 meV) was achieved. Using an effective Hamiltonian model, the effect of the competition of the spin-orbit coupling (SOC) and exchange field in the system on the valley polarization was also investigated. The magnitude of the valley splitting was found to be limited by the smaller SOC value and the induced exchange field, providing information on the enhancement of the valley polarization. A device rudiment with an anomalous valley Hall effect is proposed.