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arXiv · 1610.07425

Quantum spin Hall effect in rutile-based oxide multilayers

J. L. Lado·Daniel Guterding·Paolo Barone·Roser Valenti·V. Pardo
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Abstract

Dirac points in two-dimensional electronic structures are a source for topological electronic states due to the $\pm \pi$ Berry phase that they sustain. Here we show that two rutile multilayers (namely (WO$_2$)$_2$/(ZrO$_2$)$_n$ and (PtO$_2$)$_2$/(ZrO$_2$)$_n$, 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 $\Gamma-M$ 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.

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J. L. Lado, Daniel Guterding, Paolo Barone, Roser Valenti, V. Pardo. 2016-10-24. Quantum spin Hall effect in rutile-based oxide multilayers. https://doi.org/10.1103/physrevb.94.235111

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