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arXiv · 1707.08064

Robust zero-energy bound states in a helical lattice

Pengke Li·Jay D. Sau·Ian Appelbaum
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Abstract

Atomic-scale helices exist as motifs for several material lattices. We examine a tight-binding model for a single one-dimensional monatomic chain with a p-orbital basis coiled into a helix. A topologically nontrivial phase emerging from this model supports a zero-energy mode localized to a boundary, always embedded within a continuum band, regardless of termination site. We identify a topological invariant for this phase that is related to the number of zero energy end modes by means of the bulk-boundary correspondence, and give strict conditions for the existence of the bound state. Another, non-topological, gapped edge mode in the model spectrum has practical consequences for surface states in e.g. trigonal tellurium and selenium and other van der Waals-bonded one-dimensional semiconductors.

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Pengke Li, Jay D. Sau, Ian Appelbaum. 2017-07-25. Robust zero-energy bound states in a helical lattice. https://doi.org/10.1103/physrevb.96.115446

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