Spin-Selective Dynamic Photocurrent Response in Three-Dimensional Topological Insulators
April 12th, 2018 PAUL SEIFERT Walter Schottky Institute

Topological materials are quantum materials where the electron and spin properties are dominated by topology. Particularly, three-dimensional topological insulators are a class of Dirac materials with two-dimensional metallic surface states featuring spin-momentum locking, i.e., each momentum vector is associated with a spin locked perpendicularly to it in the surface plane. In revealing the optoelectronic dynamics in the whole range from femto- to microseconds, we demonstrate that the long surface lifetime of Bi2Te2Se-nanowires allows to access the respective surface states by a pulsed photoconduction scheme even at room temperature. Moreover, the symmetry of helicity-dependent photocurrents in Bi2Te2Se-platelets can be broken by extrinsic and intrinsic anisotropies within the circuits. In particular, we observe a helical, bias-dependent photoconductance at the lateral edges of topological Bi2Te2Se-platelets for perpendicular incidence of light, indicative of spin accumulation induced by a transversal spin Hall effect in the bulk states of the Bi2Te2Se-platelets.

Seminar, April 12, 2018, 12:00. ICFO’s Seminar Room

Hosted by Prof. Dmitri Efetov