Theory of the inverse Faraday effect due to the Rashba spin–oribt interactions: roles of band dispersions and Fermi surfaces
Theory of the inverse Faraday effect due to the Rashba spin–oribt interactions: roles of band dispersions and Fermi surfaces
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DOI：
10.1088/1367-2630/aba5be
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发表时间：
2020-07
影响因子：
3.3
通讯作者：
Y. Tanaka;T. Inoue;M. Mochizuki
中科院分区：
文献类型：
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作者：
Y. Tanaka;T. Inoue;M. Mochizuki
我们从理论上研究了逆法拉第效应，即，利用圆偏振光的自旋极化的光学诱导，特别关注带色散和费米表面在具有自旋轨道相互作用（SOI）的晶体系统中的影响。通过数值求解Rashba型SOI紧束缚模型的含时薛定谔方程，我们再现了光致自旋极化与E0 2/ω3成正比的关系，其中E0和ω分别是电场振幅和光的角频率。这种光自旋感应是由于SOI介导的光电场和电子自旋之间的动态磁电耦合。我们阐明，诱导自旋极化的大小和符号敏感地依赖于电子填充。为了理解这些结果，我们构建了一个基于Floquet定理的分析理论。该理论成功地解释了对E0和ω的依赖性，并将电子填充依赖性归因于由费米面几何形状控制的动量依赖性有效磁场。文中还讨论了与我们的理论和模型参数有关的几种候选材料和实验条件。我们的研究结果将使我们能够通过调整材料参数来设计物质的磁光响应。
We theoretically study the inverse Faraday effect, i.e., the optical induction of spin polarization with circularly polarized light, by particularly focusing on effects of band dispersions and Fermi surfaces in crystal systems with the spin–orbit interaction (SOI). By numerically solving the time-dependent Schrödinger equation of a tight-binding model with the Rashba-type SOI, we reproduce the light-induced spin polarization proportional to E02/ω3 where E0 and ω are the electric-field amplitude and the angular frequency of light, respectively. This optical spin induction is attributed to dynamical magnetoelectric coupling between the light electric field and the electron spins mediated by the SOI. We elucidate that the magnitude and sign of the induced spin polarization sensitively depend on the electron filling. To understand these results, we construct an analytical theory based on the Floquet theorem. The theory successfully explains the dependencies on E0 and ω and ascribes the electron-filling dependence to a momentum-dependent effective magnetic field governed by the Fermi-surface geometry. Several candidate materials and experimental conditions relevant to our theory and model parameters are also discussed. Our findings will enable us to engineer the magneto-optical responses of matters via tuning the material parameters.