The field of topological insulators (TIs) is rapidly growing. Concerning possible applications, the search for materials with an easily controllable TI phase is a key issue. The quantum spin Hall effect, characterized by a single pair of helical edge modes protected by time-reversal symmetry, has been demonstrated in HgTe-based quantum wells (QWs) with an inverted bandgap. We analyze the topological properties of a generically coupled HgTe-based double QW (DQW) and show how in such a system a TI phase can be driven by an inter-layer bias voltage, even when the individual layers are non-inverted. We argue, that this system allows for similar (layer-)pseudospin based physics as in bilayer graphene but with the crucial absence of a valley degeneracy.
@article{arxiv.1107.4108,
title = {Tunable quantum spin Hall effect in double quantum wells},
author = {Paolo Michetti and Jan C. Budich and Elena G. Novik and Patrik Recher},
journal= {arXiv preprint arXiv:1107.4108},
year = {2012}
}
Comments
9 pages, 8 figures, extended version (accepted Phys. Rev. B)