Giant Magneto-Optical Kerr Effect and Universal Faraday Effect in Thin-Film Topological Insulators
Giant Magneto-Optical Kerr Effect and Universal Faraday Effect in Thin-Film Topological Insulators
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, $\theta_{\mathrm{F}} = \mathrm{tan}^{-1}\,\alpha$ …