Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 33: Topological Insulators 3 (jointly with HL, MA, and O)
TT 33.2: Talk
Wednesday, March 13, 2013, 09:30–09:45, H16
Bi2Te3: A dual topological insulator — •Tomáš Rauch1, Markus Flieger1, Arthur Ernst2, Jürgen Henk1, and Ingrid Mertig1,2 — 1Martin-Luther-Universität Halle-Wittenberg, Halle, Germany — 2Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany
The class of Z2 topological insulators requires time reversal symmetry, while topological crystalline insulators require a mirror symmetry (an example is SnTe [1]).
We show that the well-known Z2 topological insulator Bi2Te3 with Z2 invariant (1; 0 0 0) is also a topological crystalline insulator with mirror Chern number −1. This dual topological character allows to dope Bi2Te3 magnetically, thereby breaking time-reversal symmetry, while keeping the topological crystalline character. As a consequence, magnetized Bi2Te3 shows a Dirac state at its (111) surface shifted off the time-reversal invariant momentum Γ, provided the magnetization is perpendicular to a mirror plane.
These fundamental features are elaborated by means of tight-binding calculations of both the bulk and the surface electronic structure as well as of the topological invariants. k→ · p→ model calculations and ab initio KKR calculations complement and support these results.
Our findings open a new path toward device applications that rely on topological insulators with magnetically controllable topological character.
[1] L. Fu, Phys. Rev. Lett. 106 (2011) 106802; T. Hsieh et alii, Nature Comms. 3 (2012) 982.