Dual topological character of chalcogenides: theory for Bi2Te3.
A topological insulator is realized via band inversions driven by the spin-orbit interaction. In the case of Z2 topological phases, the number of band inversions is odd and time-reversal invariance is a further unalterable ingredient. For topological crystalline insulators, the number of band inversions may be even but mirror symmetry is required. Here, we prove that the chalcogenide Bi2Te3 is a dual topological insulator: it is simultaneously in a Z2 topological phase with Z2 invariants (ν0;ν1ν2ν3) = (1;0 0 0) and in a topological crystalline phase with mirror Chern number -1. In our theoretical investigation we show in addition that the Z2 phase can be broken by magnetism while keeping the topological crystalline phase. As a consequence, the Dirac state at the (111) surface is shifted off the time-reversal invariant momentum Γ; being protected by mirror symmetry, there is no band gap opening. Our observations provide theoretical groundwork for opening the research on magnetic control of topological phases in quantum devices.
Department of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany.
Tomáš
T
Rauch
Department of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany.
Markus
M
Flieger
Department of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany.
Jürgen
J
Henk
Department of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany and Max Planck Institute of Microstructure Physics, 06120 Halle, Germany.
Ingrid
I
Mertig
Max Planck Institute of Microstructure Physics, 06120 Halle, Germany.
Arthur
A
Ernst