Fate of topological-insulator surface states under strong disorder

Three-dimensional topological insulators feature Dirac-like surface states which are topologically protected against the influence of weak quenched disorder. Here we investigate the effect of surface disorder beyond the weak-disorder limit using large-scale numerical simulations. We find two qualita...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2012-05, Vol.85 (20), Article 201105
Main Authors: Schubert, Gerald, Fehske, Holger, Fritz, Lars, Vojta, Matthias
Format: Article
Language:English
Subjects:
Computer simulation
Condensed matter
Diffusion
Disorders
Insulators
Quenching (cooling)
Surface layer
Three dimensional
Topology
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Summary:Three-dimensional topological insulators feature Dirac-like surface states which are topologically protected against the influence of weak quenched disorder. Here we investigate the effect of surface disorder beyond the weak-disorder limit using large-scale numerical simulations. We find two qualitatively distinct regimes: Moderate disorder destroys the Dirac cone and induces diffusive metallic behavior at the surface. Even more remarkably, for strong surface disorder a Dirac cone reappears, as new weakly disordered "surface" states emerge in the sample beneath the disordered surface layer, which can be understood in terms of an interface between a topological and an Anderson insulator. Together, this demonstrates the drastic effect of disorder on topological surface states, which cannot be captured within effective two-dimensional models for the surface states alone.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.85.201105