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arXiv · 1408.5139

Resonant Faraday and Kerr effects due to in-gap states on the surface of a topological insulator

Justin H. Wilson·Dmitry K. Efimkin·Victor M. Galitski
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Abstract

When Dirac electrons on the surface of a topological insulator are gapped, the resulting quantum anomalous Hall effect leads to universal magneto-optical Faraday and Kerr effects in the low frequency limit. However, at higher frequencies different excitations can leave their own fingerprints on the magneto-optics and can therefore be probed. In particular, we investigate the role of localized in-gap states---which inevitably appear in the presence of charged impurities---on these higher frequency magneto-optical effects. We have shown that these states resonantly contribute to the Hall conductivity and are magneto-optically active. These in-gap states lead to peculiar resonant signatures in the frequency dependence of the Faraday and Kerr angles, distinct in character to the contribution of in-gap excitonic states, and can be probed in ellipsometry measurements.

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Justin H. Wilson, Dmitry K. Efimkin, Victor M. Galitski. 2014-08-21. Resonant Faraday and Kerr effects due to in-gap states on the surface of a topological insulator. https://doi.org/10.1103/physrevb.90.205432

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