Regensburg 2013 – scientific programme
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MA: Fachverband Magnetismus
MA 5: Topological Insulators 2 (jointly with DS,HL,O,TT)
MA 5.1: Invited Talk
Monday, March 11, 2013, 15:00–15:30, H10
The THz response of topological insulator surface states — •N. Peter Armitage — The Institute of Quantum Matter, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
Topological insulators (TIs) are newly discovered states of matter characterized by an *inverted* band structure driven by strong spin-orbit coupling. One of their most touted properties is the existence of robust "topologically protected" surface states. I will discuss what topological protection means for transport experiments and how it can be probed using the technique of time-domain THz spectroscopy applied to thin films of Bi2Se3. By measuring the low frequency optical response, we can follow their transport lifetimes as we drive these materials through instabilities either by doping through a quantum phase transition into a topologically trivial regime or by reducing the film thickness. I’ll also discuss our work on the magnetic field dependence of the Kerr rotation in Bi2Se3, where we find an unprecedentedly large value of the angle of rotation of reflected light, which is due to the cyclotron resonance of the 2D Dirac fermions.