Observation of the universal magnetoelectric effect in a 3D topological insulator.

ABSTRACT: The electrodynamics of topological insulators (TIs) 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 α/4π per surface. Here we report on the observation of this so-called topological magnetoelectric effect. We use monochromatic terahertz (THz) spectroscopy of TI structures equipped with a semitransparent gate to selectively address surface states. In high external magnetic fields, we observe a universal Faraday rotation angle equal to the fine structure constant α=e²/2hc (in SI units) when a linearly polarized THz radiation of a certain frequency passes through the two surfaces of a

SUBMITTER: Dziom V 

PROVIDER: S-EPMC5440727 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature