Abstract
We investigate photocarrier dynamics in a thin film via terahertz (THz) emission spectroscopy. We report amplitude and phase modulations of the emitted THz wave under the variations in a polarization of an input laser beam and sample azimuth. Photon-helicity-dependent responses are manifested in both time and frequency domains, and azimuth dependence of such circular anisotropy exhibits a clear threefold periodicity. We analyze these results based on the symmetry of the bulk and the surface of and demonstrate that the observed helicity-dependent photocurrent originates from the circular photon drag effect, namely, linear and angular momentum transfers from photons to photocarriers.
- Received 31 August 2016
DOI:https://doi.org/10.1103/PhysRevB.94.161405
©2016 American Physical Society