Femtosecond laser excitation of FeRh/Pt bilayers launches an ultrafast pulse of electric photocurrent in the Pt-layer and thus results in emission of electromagnetic radiation in the THz spectral range. Analysis of the THz emission as a function of polarization of the femtosecond laser pulse, external magnetic field, sample temperature and sample orientation shows that photocurrent can emerge due to vertical spin pumping and photo-induced inverse spin-orbit torque at the FeRh/Pt interface. The vertical spin pumping from FeRh to Pt does not depend on the polarization of light and originates from ultrafast laser-induced demagnetization of the ferromagnetic phase of FeRh. The photo-induced inverse spin-orbit torque at the FeRh/Pt interface can be described in terms of a helicity-dependent effect of circularly polarized light on the magnetization of the ferromagnetic FeRh and subsequent generation of a photocurrent.
Ultrafast magneto-photocurrents as probe of anisotropy relaxation in GaAs
我们利用飞秒光激发在暴露于磁场中的GaAs晶体中诱导出超快光电流。磁光电流的时间分辨检测同时发射的太赫兹辐射进行了研究。我们发现，它们的动力学与其他光电流的动力学有很大的不同，这些光电流预计将遵循光强的时间形状。我们将这种差异归因于载流子各向异性弛豫对磁光电流的影响。我们的测量结果表明，在两个不同的时间尺度上发生的各向异性弛豫$10^{16}$ cm $^{-3}$和$5 \times 10^{17}$ cm $^{-3}$之间的载流子密度。慢时间常数约为100 fs，很可能受电子-声子散射的影响，而快时间常数约为10 fs，可能与价带有关。我们的研究不仅有助于更好地理解光感应电流的微观起源，但-更重要的是-表明磁光电流可以作为新的探头的各向异性弛豫GaAs。该技术适用于所有非中心对称的体半导体。
Ultrafast photo-thermoelectric currents in graphene junctions in the mid-infrared
Walter Schottky Institute and Physics Department, Technical University of Munich（慕尼黑工业大学瓦尔特·肖特基研究所和物理系）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）；TUM School of Natural Sciences, Department of Chemistry and Atomistic Modeling Center, Munich Data Science Institute, Technical University of Munich（慕尼黑工业大学自然科学学院化学系与原子模拟中心、慕尼黑数据科学研究所）；Two-Dimensional Crystal Consortium, The Pennsylvania State University（宾夕法尼亚州立大学二维晶体联盟）；Department of Materials Science and Engineering, The Pennsylvania State University（宾夕法尼亚州立大学材料科学与工程系）；Department of Chemistry, The Pennsylvania State University（宾夕法尼亚州立大学化学系）；Department of Physics, The Pennsylvania State University（宾夕法尼亚州立大学物理系）；Department of Engineering Science and Mechanics, The Pennsylvania State University（宾夕法尼亚州立大学工程力学系）
Ultrafast optical excitation of magnons in 2D antiferromagnetic semiconductors via spin torque mediated by unbound electron-hole pairs and excitons: Signatures in magnonic charge pumping
Department of Physics and Astronomy, University of Delaware（特拉华大学物理与天文学系）
