凝聚态物理
拓扑绝缘体
化学
电子
自旋极化
声子
放松(心理学)
绝热过程
自旋(空气动力学)
载流子
联轴节(管道)
表面跳跃
物理
材料科学
量子力学
心理学
社会心理学
冶金
热力学
作者
Hanqing Lu,Run Long,Wei‐Hai Fang
摘要
Ultrafast charge and spin dynamics have immense effects on the applications of topological insulators (TIs). By performing spin-adiabatic nonadiabatic molecular dynamics simulations in the presence of electron–phonon (e-ph) and spin–phonon couplings, we investigate temperature-dependent intra- and interband charge and spin relaxation dynamics via the bulk and surface paths in the three-dimensional TI Bi2Te3. The e-ph coupling dominates charge relaxation in the bulk path, and the relaxation rate is positively correlated with temperature due to the large energy gaps and weak spin polarization. Conversely, the relaxation dynamics exhibits an opposite temperature dependence in the surface path because of electron re-excitation and spin mismatching induced by spin–phonon coupling, which arises from small energy gaps and strong spin polarization. The two mechanisms rationalize the charge carriers being long-lived in the bulk and surface phases at low and room temperature, respectively. Additionally, strong thermal fluctuations of the topological states’ magnetic moments destroy the spin-momentum locking and trigger backscattering at room temperature.
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