Rashba超导体中的非线性Edelstein效应
Linear and nonlinear Edelstein effects in Rashba superconductors
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- Kyoto University（京都大学）
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中文总结 AI 辅助
本文构建包含带内和带间贡献的准经典理论，发现非线性Edelstein效应完全源于带间贡献，可作为探测量子几何带间贡献的探针。
中文摘要 AI 辅助
我们构建了超导体中Edelstein效应的准经典理论，该理论同时包含了带内和带间贡献。为了描述在传统最低阶准经典表述中缺失的带间贡献，我们在存在反对称自旋轨道耦合的情况下推导了增强的Eilenberger方程。带内贡献则使用多带Eilenberger方程进行评估。我们将这些公式应用于s波Rashba超导体中超流感应表面自旋磁化，并研究了其对温度、距表面距离、自旋轨道耦合强度和超流的依赖关系。带内贡献源于超流引起的具有相反动量和自旋极化的准粒子不对称性，而带间贡献则源于由Rashba自旋轨道势的动量导数产生的反常速度项。在螺旋度基中，该反常速度项用与Rashba本征态动量依赖性相关的Berry联络来表示。带内贡献随自旋轨道耦合强度线性增加，而带间贡献表现出非单调依赖，当Rashba自旋劈裂与超导能隙相当时达到最大值。此外，在我们考虑的清洁s波Rashba模型中，我们发现磁化对超流的非线性依赖完全来自带间贡献。因此，尽管带内贡献主导线性Edelstein效应，非线性Edelstein效应可以作为探测源于量子几何的带间贡献的有用工具。
英文摘要
We formulate a quasiclassical theory of the Edelstein effect in superconductors that incorporates both intraband and interband contributions. To describe the interband contribution, which is absent from the conventional leading-order quasiclassical formulation, we derive augmented Eilenberger equations in the presence of antisymmetric spin-orbit coupling. The intraband contribution is evaluated using multiband Eilenberger equations. We apply these formulations to supercurrent-induced surface spin magnetization in $s$-wave Rashba superconductors and investigate its dependence on temperature, distance from the surface, spin-orbit coupling strength, and supercurrent. The intraband contribution originates from a supercurrent-induced asymmetry of quasiparticles with opposite momenta and spin polarizations, whereas the interband contribution arises from the anomalous-velocity term generated by the momentum derivative of the Rashba spin-orbit potential. In the helicity basis, this anomalous-velocity term is expressed in terms of the Berry connection associated with the momentum dependence of the Rashba eigenstates. The intraband contribution increases linearly with the spin-orbit coupling strength, whereas the interband contribution exhibits a nonmonotonic dependence and is maximized when the Rashba spin splitting is comparable to the superconducting gap. Moreover, within the clean $s$-wave Rashba model considered here, we find that the nonlinear dependence of magnetization on the supercurrent arises solely from the interband contribution. Thus, although the intraband contribution dominates the linear Edelstein effect, the nonlinear Edelstein effect can serve as a useful probe of the interband contribution originating from quantum geometry.
