Anomalous galvanomagnetism, cyclotron resonance, and microwave spectroscopy of topological insulators

The surface quantum Hall state, magnetoelectric phenomena, and their connection to axion electrodynamics have been studied intensively for topological insulators. One of the obstacles for observing such effects comes from nonzero conductivity of the bulk. To overcome this obstacle, we propose to use an external magnetic field to suppress the conductivity of the bulk carriers. The magnetic field dependence of galvanomagnetic and electromagnetic responses of the whole system shows anomalies due to broken time-reversal symmetry of the surface quantum Hall state, which can be used for its detection. In particular, we find negative linear dc magnetoresistivity and a quadratic field dependence of the Hall angle, shifted rf cyclotron resonance, nonanalytic microwave transmission coefficient, and saturation of the Faraday rotation angle with increasing magnetic field or wave frequency.