基于第一性原理的锗中应变可调自旋弛豫
Strain-Tunable Spin Relaxation in Germanium from First Principles
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中文总结 AI 辅助
本研究从第一性原理结合杂化泛函能带结构与全相对论电子-声子相互作用，预测锗的自旋弛豫等性质，发现双轴压应变可显著提升空穴自旋寿命，为量子技术提供实用方案。
中文摘要 AI 辅助
锗是半导体自旋量子比特和自旋电子学的领先平台，但其电子和空穴的自旋动力学主要通过唯象模型理解。本文完全从第一性原理预测体相锗的电子输运和自旋弛豫，结合杂化泛函能带结构与全相对论电子-声子（$e$-ph）相互作用，无需经验参数，预测的载流子迁移率、速度-电场曲线及100-400 K范围内的电子和空穴自旋弛豫时间与实验结果高度吻合。通过按谷和声子模式解析自旋翻转散射，确定了控制自旋弛豫的微观机制，表明自旋弛豫与动量弛豫虽均由$e$-ph散射介导，但受不同过程控制。进一步研究显示，双轴压应变在5%应变下可将空穴自旋寿命提升最多两个数量级，该效应源于应变诱导的价带分裂和被抑制的自旋混合，此机制与锗-on-硅器件直接相关，应变可为量子技术中工程化长寿命空穴自旋提供实用途径。
英文摘要
Germanium is a leading platform for semiconductor spin qubits and spintronics. Yet its electron and hole spin dynamics remain understood primarily through phenomenological models. Here, we predict electronic transport and spin relaxation in bulk Ge entirely from first principles, combining hybrid-functional band structures with fully relativistic electron-phonon ($e$-ph) interactions. Without empirical parameters, we predict carrier mobilities, velocity-field curves, and electron and hole spin relaxation times in close agreement with experiments over 100$-$400 K. By resolving spin-flip scattering by valley and phonon mode, we identify the microscopic mechanisms governing spin relaxation and show that spin and momentum relaxation, although both mediated by $e$-ph scattering, are controlled by distinct processes. We further show that compressive biaxial strain enhances the hole spin lifetime by up to two orders of magnitude at 5% strain, through strain-induced valence-band splitting and suppressed spin mixing. This mechanism is directly relevant to Ge-on-Si devices, where strain provides a practical route to engineering long-lived hole spins for quantum technologies.
发表机构
- California Institute of Technology（加州理工学院）
- Pohang University of Science and Technology（浦项科技大学）
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