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arXiv · 1709.03935

Entanglement entropy and entanglement spectrum of Bi$_{1-x}$Sb$_{x}$ (111) bilayers

M. Brzezińska·M. Bieniek·T. Woźniak·P. Potasz·A. Wójs
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Abstract

We investigate topological properties of Bi$_{1-x}$Sb$_{x}$ bilayers in the (111) plane using entanglement measures. Electronic structures are studied using multi-orbital tight-binding model, with structural stability confirmed through first-principles calculations. Topologically non-trivial nature of Bi bilayer is proved by the presence of spectral flow in the entanglement spectrum. We consider topological phase transitions driven by a composition change $x$, an applied external electric field in pure Bi, and strain in pure Sb. Composition- and strain-induced phase transitions reveal a finite discontinuity in the entanglement entropy. However, this quantity remains a continuous function of electric field strength, but shows a discontinuity in the first derivative. We relate the difference in behavior of the entanglement entropy to breaking of the inversion symmetry in the last case.

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M. Brzezińska, M. Bieniek, T. Woźniak, P. Potasz, A. Wójs. 2017-09-12. Entanglement entropy and entanglement spectrum of Bi$_{1-x}$Sb$_{x}$ (111) bilayers. https://doi.org/10.1088/1361-648x%2Faaaf54

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