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arXiv · 2003.09498

Impurity bound states as detectors of topological band structures revisited

Seydou-Samba Diop·Lars Fritz·Matthias Vojta·Stephan Rachel
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Abstract

Band structures of topological insulators are characterized by non-local topological invariants. Consequently, proposals for the experimental detection using local probes are rare. A recent paper [Slager et al., Phys. Rev. B 92, 085126 (2015)] has argued, based on theoretical results for a particular class of models, that insulators with topologically trivial and non-trivial band structures in two space dimensions display a qualitatively different response to point-like impurities. Here we present a comprehensive investigation of the impurity response of a large set of models of non-interacting electrons on the honeycomb lattice, driven insulating by either broken inversion, broken time reversal, broken $C_3$, or broken translation symmetry. These cases include Hofstadter bands, strain-induced pseudo-Landau levels and higher-order topological insulators. Our results confirm that for hopping models respecting the lattice symmetries, the response to a single impurity can indeed distinguish between trivial and non-trivial band topology. However, for modulated or inhomogeneous host systems we find that trivial states of matter can display an impurity response akin to that of topologically non-trivial states, and thus the diagnostic fails.

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Seydou-Samba Diop, Lars Fritz, Matthias Vojta, Stephan Rachel. 2020-03-20. Impurity bound states as detectors of topological band structures revisited. https://doi.org/10.1103/physrevb.101.245132

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