"Dynamical axion field in topological magnetic insulators"

Rundong Li: Jing Wang, Xiao-Liang Qi and Shou-Cheng Zhang; Nature Physics, 03/15/10.

Additional Authors: Jing Wang, Xiao-Liang Qi and Shou-Cheng Zhang

Abstract:

Axions are weakly interacting particles of low mass, and were postulated more than 30 years ago in the framework of the Standard Model of particle physics. Their existence could explain the missing dark matter of the Universe. However, despite intensive searches, axions have yet to be observed. Here we show that magnetic fluctuations of topological insulators couple to the electromagnetic fields exactly like the axions, and propose several experiments to detect this dynamical axion field. In particular, we show that the axion coupling enables a nonlinear modulation of the electromagnetic field, leading to attenuated total reflection. We propose a new optical-modulator device based on this principle.