Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116, Braunschweig, Germany.
Leibniz Institute of Photonic Technology, 07745, Jena, Germany.
Sci Rep. 2017 Sep 11;7(1):11241. doi: 10.1038/s41598-017-11603-4.
The anomalous Hall (AH) and spin Hall effects are important tools for the generation, control, and detection of spin and spin-polarized currents in solids and, thus, hold promises for future spintronic applications. Despite tremendous work on these effects, their ultrafast dynamic response is still not well explored. Here, we induce ultrafast AH currents in a magnetically-biased semiconductor by optical femtosecond excitation at room temperature. The currents' dynamics are studied by detecting the simultaneously emitted THz radiation. We show that the temporal shape of the AH currents can be extracted by comparing its THz radiation to the THz radiation emitted from optically induced currents whose temporal shape is well known. We observe a complex temporal shape of the AH currents suggesting that different microscopic origins contribute to the current dynamics. This is further confirmed by photon energy dependent measurements revealing a current inversion at low optical excitation intensities. Our work is a first step towards full time resolution of AH and spin Hall currents and helps to better understand the underlying microscopic origins, being a prerequisite for ultrafast spintronic applications using such currents.
反常霍尔（AH）和自旋霍尔效应是在固体中产生、控制和检测自旋和自旋极化电流的重要工具，因此有望应用于未来的自旋电子学。尽管对这些效应进行了大量的研究，但它们的超快动态响应仍未得到很好的探索。在这里，我们通过室温下的飞秒光学激发在磁性偏置半导体中诱导超快 AH 电流。通过探测同时发射的太赫兹辐射来研究电流的动力学。我们表明，可以通过将 AH 电流的太赫兹辐射与太赫兹辐射进行比较来提取其时间形状，太赫兹辐射是由其时间形状众所周知的光致电流发射的。我们观察到 AH 电流的复杂时间形状表明不同的微观起源对电流动力学有贡献。这进一步通过光子能量相关测量得到证实，该测量揭示了在低光激发强度下的电流反转。我们的工作是实现 AH 和自旋霍尔电流全时间分辨率的第一步，并有助于更好地理解潜在的微观起源，这是利用这些电流进行超快自旋电子学应用的前提。
