You are here: Home / Seminars / Seminar Database / Special CAMP: Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

Special CAMP: Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator

Main Content

Peter Armitage, Johns Hopkins University
When
19 April 2017 from 3:00 PM to 4:00 PM
Where
318 Osmond Laboratory
Contact Name
Chaoxing Liu
Add event to calendar
vCal
iCal

Topological insulators have been proposed to be best characterized as bulk magnetoelectric materials that show response functions quantized in terms of fundamental physical constants. Here we lower the chemical potential of three-dimensional (3D) Bi2Se3 films to ∼30 meV above the Dirac point, and probe their low-energy electrodynamic response in the presence of magnetic fields with high-precision time-domain terahertz polarimetry. For fields higher than 5 T, we observed quantized Faraday and Kerr rotations, whereas the DC transport is still semi-classical. A non-trivial Berry phase offset to these values gives evidence for axion electrodynamics and the topological magnetoelectric effect. The time structure used in these measurements allows a direct measure of the fine structure constant based on a topological invariant of a solid-state system.

Seminars