Zhao Chuanyu, Zheng Qijing, Zhao Jin
Department of Physics, ICQD/Hefei National Research Center for Physical Sciences at the Microscale, and CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
Fundam Res. 2022 Mar 18;2(4):506-510. doi: 10.1016/j.fmre.2022.03.006. eCollection 2022 Jul.
We perform an non-adiabatic molecular dynamics simulation to investigate the non-equilibrium spin and electron dynamics in a prototypical topological insulator (TI) BiSe. 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 100 fs. This study provides critical insights into the non-equilibrium electron and spin dynamics in TI at the level and paves a way for the design of ultrafast spintronic materials.
我们进行了非绝热分子动力学模拟，以研究典型拓扑绝缘体（TI）BiSe中的非平衡自旋和电子动力学。与基态不同，我们发现，在非平衡动力学中，时间反演对拓扑表面态（TSSs）之间可以以振荡的方式发生背散射。分析表明，声子激发通过电子 - 声子相互作用诱导轨道成分变化，进而通过自旋 - 轨道耦合进一步激发自旋倾斜。时间反演对TSSs的自旋倾斜导致它们之间非零的非绝热耦合，进而引发背散射。自旋倾斜和背散射都导致了超快自旋弛豫，其时间尺度约为100飞秒。这项研究为TI中电子和自旋的非平衡动力学提供了关键见解，并为超快自旋电子材料的设计铺平了道路。
