title: Reading charge transport from the spin dynamics on the surface of a topological insulator.
abstract: Resolving the conductance of the topological surface states (TSSs) from the bulk contribution has been a great challenge for studying the transport properties of topological insulators. By developing a nonperturbative diffusion equation that describes fully the spin-charge dynamics in the strong spin-orbit coupling regime, we present a proposal to read the charge transport information of TSSs from its spin dynamics which can be isolated from the bulk contribution by the time-resolved second harmonic generation pump-probe measurement. We demonstrate the qualitatively different Dyaknov-Perel spin relaxation behavior between the TSSs and the two-dimensional spin-orbit coupling electron gas. The decay time of both in-plane and out-of-plane spin polarization is naturally proved to be identical to the charge transport time. The out-of-plane spin dynamics is shown to be in the experimentally reachable regime of the femtosecond pump-probe spectroscopy and thereby we suggest experiments to detect the charge transport properties of the TSSs from their unique spin dynamics.
authors.affiliation: Department of Physics, Texas A&M University, College Station, Texas 77843-4242, USA and Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Jairo
authors.initials: J
authors.lastname: Sinova