Abstract
Topological insulators have been attracting much attention as potential candidates for spintronic applications. Spin-momentum-locked surface states can lead to spin current naturally accompanied by electric charge current. As a way to control the current, circularly polarized photon injection has been widely used as the photon can excite spin-polarized carriers selectively depending on the photon's helicity. Here, the authors investigate the helicity-dependent photocarrier dynamics in an unbiased Bi${}_{2}$Se${}_{3}$ thin film by monitoring the terahertz pulse emitted from the sample after illumination by femtosecond laser pulses. Although all the measurements were performed on an unbiased sample with no electrical contacts, the authors observe three-fold periodic helicity-dependent terahertz emission, and attribute such circular anisotropy in the photocurrent to the circular photon drag effect, namely linear and angular momentum transfer from photons to photocarriers.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
