Shift Charge and Spin Photocurrents in Dirac Surface States of Topological Insulator

Dr. Kun Woo Kim, KIAS

Dec. 9(Fri), 4p.m., #1323(E6-2. 1st fl.

The generation of photocurrent in condensed matter is of main interest for photovoltaic and opto-electronic applications. Shift current, a nonlinear photoresponse, has attracted recent intensive attention as a dominant player of bulk photovoltaic effect in ferroelectric materials. In three-dimensional topological insulators Bi₂X₃ (X: Te, Se), we find that Dirac surface states with a hexagonal warping term support shift current by linearly polarized light. Moreover, we study ‘shift spin current’ that arises in Dirac surface states by introducing time-reversal symmetry breaking perturbation. The estimate for the magnitudes of the shift charge and spin current densities are 0.13 I₀ and 0.40 I₀ (nA/m) for Bi₂Te₃ with the intensity of light I₀ measured in (W/m²), respectively, which can offer a useful method to generate these currents efficiently.

Contact: MyungJoon Han, Physics Dept., (mj.han@kaist.ac.kr)