巡游贡献对轨道角动量弛豫与动力学的关键作用

中文摘要 AI 辅助

轨道角动量（OAM）是一种有望用于低耗散输运和磁化控制的自有度，然而其弛豫机制仍存在争议，原子中心近似（ACA）预测的OAM扩散长度远短于实验值。我们利用第一性原理Lindbladian密度矩阵动力学解决了这一差异，该方法捕获了电子-声子散射和巡游OAM贡献，并结合了分离ACA与巡游组分的第一性原理参数化紧束缚方法。在强自旋-轨道耦合（SOC）体系MoS2中，轨道弛豫呈现多时间尺度特征，先是快速的谷间重新分布，随后是与自旋耦合的较慢衰减。在弱SOC的硅烯中，自旋与轨道动力学解耦；电场可调控自旋弛豫，而轨道寿命保持不变。在两种材料中，ACA轨道寿命比巡游轨道寿命至少短一个数量级，这是由于晶体场劈裂驱动的超快进动所致，而该劈裂在巡游组分中不存在。这些结果表明，超越原子中心模型对于描述轨道弛豫和扩散至关重要。

英文摘要

Orbital angular momentum (OAM) is a promising degree of freedom for low-dissipation transport and magnetization control, yet its relaxation mechanisms remain controversial, with atomcentered approximations (ACA) predicting much shorter OAM diffusion lengths than experiments. We address this discrepancy using first-principles Lindbladian density-matrix dynamics, capturing electron-phonon scattering and itinerant OAM contributions, together with a first-principles parameterized tight-binding approach that separates the ACA and itinerant components. In MoS2,a strong-spin-orbit-coupling (SOC) system, orbital relaxation is multi-timescale, with fast intervalley redistribution followed by slower decay coupled to the spin. In weak-SOC silicene, spin and orbital dynamics decouple; an electric field tunes spin relaxation while leaving orbital lifetimes unchanged. In both materials, ACA orbital lifetimes are at least one order of magnitude shorter than itinerant ones, due to ultrafast precession driven by crystal-field splitting, absent from the itinerant component. These results demonstrate that going beyond atom-centered models is essential for describing orbital relaxation and diffusion.

发表机构

• University of Wisconsin-Madison（威斯康星大学麦迪逊分校）
• Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST（加泰罗尼亚纳米科学和纳米技术研究所（ICN2，CSIC和BIST））
• Universitat Autònoma de Barcelona (UAB)（巴塞罗那自治大学）

机构由 AI 辅助整理，请以论文原文为准。