%0 Journal Article
%T Robustness of Quantum Spin Hall Effect in an External Magnetic Field
%A Song-Bo Zhang
%A Yan-Yang Zhang
%A Shun-Qing Shen
%J Physics
%D 2014
%I arXiv
%R 10.1103/PhysRevB.90.115305
%X The edge states in the quantum spin Hall effect are expected to be protected by time reversal symmetry. The experimental observation of the quantized conductance was reported in the InAs/GaSb quantum well {[}Du et al, arXiv:1306.1925{]}, up to a large magnetic field, which raises a question on the robustness of the edge states in the quantum spin Hall effect under time reversal symmetry breaking. Here we present a theoretical calculation on topological invariants for the Benevig-Hughes-Zhang model in an external magnetic field, and find that the quantum spin Hall effect retains robust up to a large magnetic field. The critical value of the magnetic field breaking the quantum spin Hall effect is dominantly determined by the band gap at the $\Gamma$ point instead of the indirect band gap between the conduction and valence bands. This illustrates that the quantum spin Hall effect could persist even under time reversal symmetry breaking.
%U http://arxiv.org/abs/1408.6734v2