摘要
We perform an ab initio non-adiabatic molecular dynamics simulation to investigate the non-equilibrium spin and electron dynamics in a prototypical topological insulator(TI)Bi,Ses.Different from the ground state,we reveal that backscattering can happen in an oscillating manner between time-reversal pair topological surface states(TSSs)in the non-equilibrium dynamics.Analysis shows the phonon excitation induces orbital composition change by electron-phonon interaction,which further stimulates spin canting through spin-orbit coupling.The spin canting of time-reversal pair TSSs leads to the non-zero non-adiabatic coupling between them and then issues in backscattering.Both the spin canting and backscattering result in ultrafast spin relaxation with a timescale around 10o fs.This study provides critical insights into the non-equilibrium electron and spin dynamics in TI at the ab initio level and paves a way for the design of ultrafast spintronic materials.
基金
supported by National Key R&D Program of China(Grant No.2017YFA0204904)
National Natural Science Foundation of China(Grants No.11620101003 and 11974322)Anhui Initiative in Quantum Information Technologies(Grant No.AHY090300).Calculations were performed at Environmental Molecular Sciences Laboratory at the Pacific Northwest National Laboratory,a user facility sponsored by the Us Department of Energy Office of Biological and Environmental Research.
