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Topological Crystalline Insulator in a New Bi Semiconducting Phase

Authors: F. Munoz, M.G. Vergniory, T. Rauch, J. Henk, E.V. Chulkov, I. Mertig, S. Botti, M.A.L. Marques, and A.H. Romero

Ref.: Sci. Rep. 6, 21790 (2016)

Abstract: Topological crystalline insulators are a type of topological insulators whose topological surface states are protected by a crystal symmetry, thus the surface gap can be tuned by applying strain or an electric field. In this paper we predict by means of ab initio calculations a new phase of Bi which is a topological crystalline insulator characterized by a mirror Chern number nM = −2, but not a Z2 strong topological insulator. This system presents an exceptional property: at the (001) surface its Dirac cones are pinned at the surface high-symmetry points. As a consequence they are also protected by time-reversal symmetry and can survive against weak disorder even if in-plane mirror symmetry is broken at the surface. Taking advantage of this dual protection, we present a strategy to tune the band-gap based on a topological phase transition unique to this system. Since the spin-texture of these topological surface states reduces the back-scattering in carrier transport, this effective band-engineering is expected to be suitable for electronic and optoelectronic devices with reduced dissipation.

Citations: 5 (Google scholar)

DOI: 10.1038/srep21790