First experiments with ultrashort, circularly polarized soft X-ray pulses at FLASH2
S. Marotzke, D. Gupta, R. -P. Wang, M. Pavelka, S. Dziarzhytski, C. von Korff Schmising, S. Jana, N. Thielemann-Kühn, T. Amrhein, M. Weinelt, I. Vaskivskyi, R. … 展开作者
S. Marotzke, D. Gupta, R. -P. Wang, M. Pavelka, S. Dziarzhytski, C. von Korff Schmising, S. Jana, N. Thielemann-Kühn, T. Amrhein, M. Weinelt, I. Vaskivskyi, R. Knut, D. Engel, M. Braune, M. Ilchen, S. Savio, T. Otto, K. Tiedtke, V. Scheppe, J. Rönsch-Schulenberg, E. Schneidmiller, C. Schüßler-Langeheine, H. A. Dürr, M. Beye, G. Brenner, N. Pontius
Time-resolved absorption spectroscopy as well as magnetic circular dichroism with circularly polarized soft X-rays (XAS and XMCD) are powerful tools to probe electronic and magnetic dynamics in magnetic materials element- and site-selectively. Employing these methods, groundbreaking results have been obtained for instance for magnetic alloys, which helped to fundamentally advance the field of ultrafast magnetization dynamics. At the free electron laser facility FLASH key capabilities for ultrafast XAS and XMCD experiments have recently improved: In an upgrade, an APPLE-III helical afterburner undulator was installed at FLASH2 in September 2023. This installation allows for the generation of circularly polarized soft X-ray pulses with a duration of a few tens of femtoseconds covering the L3,2-edges of the important 3d transition metal elements with pulse energies of several uJ. Here, we present first experimental results with such ultrashort X-ray pulses from the FL23 beamline employing XMCD at the L-edges of the 3d metals, Co, Fe and Ni. We obtain significant dichroic difference signals indicating a degree of circular polarization close to 100%. With the pulse-length preserving monochromator at beamline FL23 and an improved pump laser setup, FLASH can offer important and efficient experimental instrumentation for studies on ultrafast spin dynamics in 3d transition metals, multilayers, and alloys.
Spin current and magnetization induced by circularly polarized synchrotron radiation in magnetically-doped topological insulator Bi$_{1.37}$V$_{0.03}$Sb$_{0.6}$Te$_2$Se
提出了磁掺杂拓扑绝缘体Bi $_{1.37}$ V $_{0.03}$ Sb $_{0.6}$ Te $_2$ Se中利用圆极化同步辐射产生自旋极化电流和相应的诱导磁化的空穴诱导机制.考虑自旋极化电流的产生是由于自旋相关的狄拉克锥拓扑表面态在费米能级和随后的补偿所产生的空穴的人口减少。我们从实验和理论上找到了产生的自旋极化电流与电化学电势移动之间的关系。从实验和理论上证实了圆偏振同步辐射诱导的面外磁化和通过改变圆偏振方向引起的面外磁化反转。
Planar chiral nanoantenna for excitation-chirality-controlled hot spot modulation and emitter-coupled circularly polarized emission
Friedrich Schiller University Jena（耶拿弗里德里希·席勒大学）；Abbe Center of Photonics, Friedrich Schiller University Jena（耶拿弗里德里希·席勒大学阿贝光学中心）；Leibniz Institute of Photonic Technology（莱布尼茨光子技术研究所）；University of Würzburg（维尔茨堡大学）；The Australian National University（澳大利亚国立大学）；Academia Sinica（中央研究院）；National Yang Ming Chiao Tung University（国立阳明交通大学）
