Dirac points in two-dimensional electronic structures are a source for topological electronic states due to the ±π Berry phase that they sustain. Here we show that two rutile multilayers (namely (WO2)2/(ZrO2)n and (PtO2)2/(ZrO2)n, where an active bilayer is sandwiched by a thick enough (n=6 is sufficient) band insulating substrate, show semi-metallic Dirac dispersions with a total of four Dirac cones along the Γ−M direction. These become gapped upon the introduction of spin-orbit coupling, giving rise to an insulating ground state comprising four edge states. We discuss the origin of the lack of topological protection in terms of the valley spin-Chern numbers and the multiplicity of Dirac points. We show with a model Hamiltonian that mirror-symmetry breaking would be capable of creating a quantum phase transition to a strong topological insulator, with a single Kramers pair per edge.
@article{arxiv.1610.07425,
title = {Quantum spin Hall effect in rutile-based oxide multilayers},
author = {J. L. Lado and Daniel Guterding and Paolo Barone and Roser Valenti and V. Pardo},
journal= {arXiv preprint arXiv:1610.07425},
year = {2016}
}