Spin Caloritronics in III-V-Semiconductors

我们建议探讨的潜力，电气和时间分辨光学方法研究热诱导自旋输运现象的III-V族半导体异质结构。在第一个焦点，我们将产生相干自旋和电荷包的光激光脉冲。应通过时间分辨法拉第旋转（自旋敏感）和时间分辨透射（电荷敏感）的时空测量，在横向温度梯度中探测其热导率。通过产生平行和垂直于入射线偏振激光束的初始自旋方向，我们期望能够探索热诱导自旋输运的自旋轨道耦合的作用。在第二个焦点，我们建议研究是否，在类似的电压梯度，温度梯度单独的结果（I）自旋极化或（II）自旋电流。在（I）中，我们研究了由于热致电场引起的内部磁场是否会产生自旋极化。在（II）中，我们建议测量自旋能斯特效应，其中自旋电压预期横向于热梯度的方向。自旋电压应通过磁光探针或光电电压或反向自旋霍尔效应的电测量进行测量，使用铂电极作为探测器。

We propose to explore the potential of electrical and time-resolved optical methods for investigating heat-induced spin transport phenomena in III-V semiconductor heterostructures. In a first focus, we will generate coherent spin and charge packets by optical laser pulses. Their thermal conductivities shall be probed in a lateral temperature gradient by spatio-temporal measurements of time-resolved Faraday rotation (spin sensitive) and time-resolved transmission (charge sensitive). By generating initial spin directions parallel and perpendicular to the incident linearly polarized laser beam, we expect being able to explore the role of spin-orbit coupling for heat-induced spin transport. In a second focus, we propose to study whether, in analogy to a voltage gradient, a temperature gradient alone results in (I) a spin polarization or (II) a spin current. In (I), we study if a spin polarization will be created by internal magnetic fields, which are due to thermally-induced electric fields. In (II), we suggest to measure the spin- Nernst effect, for which a spin voltage is expected transverse to the direction of the thermal gradient. The spin voltage shall be measured either by magneto-optical probes or by electrical measurements of the photo-voltage or of the inverse spin Hall effect using platinum electrodes as detectors.