Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Frontiers of Electronic Structure Theory: Focus on Topology and Transport III
O 62.1: Topical Talk
Mittwoch, 9. März 2016, 15:00–15:30, H24
Topological semimetal phases in strained HgTe-based alloys — Tomáš Rauch1, Steven Achilles1, •Jürgen Henk1, and Ingrid Mertig1,2 — 1Martin Luther University Halle-Wittenberg, Halle, Germany — 2Max Planck Institute of Microstructure Physics, Halle, Germany
Topological insulators (TIs) have matured to a class of materials that is studied worldwide with great effort. Prominent examples are HgTe, the Bi chalcogenides, and SnTe. Recently, the set of “original” TIs has been extended by topological semimetals: the topological Dirac and the Weyl semimetals, both of them showing point-like Fermi surfaces in the bulk. Weyl points appear always in pairs with opposite topological charges of ± 1; their projections onto the surface Brillouin zone are connected by a Fermi arc, i. e. a sizably spin-polarized topological surface state with an open Fermi contour.
In this presentation I report on theoretical investigations of strained HgTe1−xSx alloys [1], with surprising results. (i) In the strong TI phase, the spin chirality of the topological nontrivial surface state can be reversed by moderate strain and changing the alloy concentration x. (ii) On top of this, we observe a Dirac and a Weyl semimetal phase. These findings call for experimental verification and extend significantly the “topological playground” for spin-dependent transport.
[1] T. Rauch, S. Achilles, JH, I. Mertig, Phys. Rev. Letters 114 (2015) 236805.