Topological Phase Transition Coupled with Spin-Valley Physics in Ferroelectric Oxide Heterostructures

The possibility to engineer the coupling of spin and valley physics is explored in ferroelectric oxide heterostructures with eg electronic configuration. We show that the polar structural distortion induces the appearance of spin-valley coupled properties, at the same time being responsible for a topological transition from a quantum spin-Hall insulating phase to a trivial band insulator. The coupled spin-valley physics is affected by the topological band inversion in a non-trivial way; while the valley-dependent spin polarization of both conduction and valence bands is preserved, a change of the Berry curvature and of spin-valley selection rules is predicted, leading to different circular dichroic response as well as valley and spin Hall effects.