Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 70: Topological Insulators I (joined session with TT)

HL 70.4: Talk

Thursday, March 23, 2017, 10:30–10:45, POT 251

Engineering topological phases in crystalline symmetry-protected monolayers — •Chengwang Niu, Patrick M. Buhl, Gustav Bihlmayer, Daniel Wortmann, Stefan Blügel, and Yuriy Mokrousov — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

The properties that distinguish topological crystalline insulators (TCIs) and topological insulators (TIs) rely on crystalline symmetry and time-reversal symmetry, respectively, which encodes different surface/edge properties. Here, we predict theoretically that TlM, thallium chalcogenide, (M = S and Se) (110) monolayers realize a family of two-dimensional (2D) TCIs characterized by mirror Chern number C_M =−2 with an even number of band inversions. [1] Remarkably, under uniaxial strain (≈ 1%), a topological phase transition between 2D TCI and 2D TI is revealed in TlM. In contrast, for Na₃Bi, the band inversion occur at single k point, thus a coexistence of 2D TI and 2D TCI is obtained. [2] Finally, we show different edge-state behaviors, especially at the time reversal invariant points.

This work was supported by SPP 1666 of the DFG.

[1] C. Niu, P. M. Buhl, G. Bihlmayer, D. Wortmann, S. Blügel, and Y. Mokrousov, Nano Lett. 15, 6071 (2015).

[2] C. Niu, P. M. Buhl, G. Bihlmayer, D. Wortmann, S. Blügel, and Y. Mokrousov, submitted.