Giant magneto-optical Kerr effect and universal Faraday effect in thin-film topological insulators

Topological insulators can exhibit strong magneto-electric 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...

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Bibliographic Details
Published in:Physical review letters 2010-07, Vol.105 (5), p.057401-057401, Article 057401
Main Authors: Tse, Wang-Kong, MacDonald, A H
Format: Article
Language:English
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Summary:Topological insulators can exhibit strong magneto-electric 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 θF=tan(-1)α, where α is the vacuum fine structure constant, and that it has a giant Kerr rotation θK=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.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.105.057401