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arXiv · 1003.2260

Giant Magneto-optical Kerr Effect and Universal Faraday Effect in Thin-film Topological Insulators

Wang-Kong Tse·A. H. MacDonald
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Abstract

Topological insulators can exhibit strong magnetoelectric effects when their time-reversal symmetry is broken. In this Letter we consider the magneto-optical Kerr and Faraday effects of a topological insulator thin film weakly exchange-coupled to a ferromagnet. We find that its Faraday rotation has a universal value at low-frequencies, $θ_{\mathrm{F}} = \mathrm{tan}^{-1}\,α$ where $α$ is the vacuum fine structure constant, and that it has a giant Kerr rotation $θ_{\mathrm{K}} = π/2$. These properties follow from a delicate interplay between thin-film cavity confinement and the surface Hall conductivity of a topological insulator's helical quasiparticles.

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Wang-Kong Tse, A. H. MacDonald. 2010-07-27. Giant Magneto-optical Kerr Effect and Universal Faraday Effect in Thin-film Topological Insulators. https://doi.org/10.1103/physrevlett.105.057401

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