Abstract
Dirac points in two-dimensional electronic structures are a source for topological electronic states due to the Berry phase that they sustain. Here we show that two rutile multilayers [namely and ], where an active bilayer is sandwiched by a thick enough ( is sufficient) band insulating substrate, show semimetallic Dirac dispersions with a total of four Dirac cones along the 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.
- Received 24 October 2016
DOI:https://doi.org/10.1103/PhysRevB.94.235111
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