Electron– versus Spin–Phonon Coupling Governs the Temperature-Dependent Carrier Dynamics in the Topological Insulator Bi2Te3,Journal of the American Chemical Society

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Electron– versus Spin–Phonon Coupling Governs the Temperature-Dependent Carrier Dynamics in the Topological Insulator Bi2Te3
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2023-11-15 , DOI: 10.1021/jacs.3c10561
Haoran Lu ₁ , Run Long ₁ , Wei-Hai Fang ₁

Affiliation

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.

中文翻译：

电子与自旋声子耦合控制拓扑绝缘体 Bi2Te3 中与温度相关的载流子动力学

超快电荷和自旋动力学对拓扑绝缘体（TI）的应用具有巨大影响。通过在存在电子-声子 ( e - ph ) 和自旋-声子耦合的情况下进行自旋绝热非绝热分子动力学模拟，我们通过三个通道中的体积和表面路径研究了温度依赖性带内和带间电荷以及自旋弛豫动力学。维TI Bi ₂ Te ₃。e - ph耦合主导体路径中的电荷弛豫，并且由于能隙大和自旋极化弱，弛豫率与温度正相关。相反，由于小能隙和强自旋极化引起的自旋声子耦合引起的电子重激发和自旋失配，弛豫动力学在表面路径中表现出相反的温度依赖性。这两种机制合理地解释了载流子分别在低温和室温下在体相和表面相中的长寿命。此外，拓扑态磁矩的强烈热波动破坏了自旋动量锁定并触发室温下的反向散射。

更新日期：2023-11-15

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