SFB/TRR21 Colloquium Talk 18.11.16 14:00 Rm. 2.136
Speaker: Andrei Pimenov, Title: Universal Faraday rotation in topological insulators
Topological insulators are materials which are insulating in the bulk and which reveal conducting surface/edge states. These states are topologically protected against non-magnetic scattering due to their chiral nature. The electrodynamics of topological insulators is described by modified Maxwell’s equations, which contain additional terms that couple an electric field to a magnetization and a magnetic field to a polarization of the medium, such that the coupling coefficient is quantized in odd multiples of e2/2hc per surface. The new term leads to universal values of Faraday rotation angle equal to the fine structure constant α ≈ 1/137 rad when a linearly polarized THz radiation passes through the two surfaces of a topological insulator. These experiments may potentially be used for a metrological definition of the three basic physical constants.