Controlling magnetic textures such as domain walls lies at the heart of modern spintronics, and fast, energy-efficient approaches are actively being explored. In this seminar, I present two contrasting strategies—employing either electrical or optical stimuli—to manipulate spin textures in distinct material systems, probed via magneto-optical microscopy. In the first part, I focus on ultrafast time-resolved magneto-optical Kerr effect imaging of current-induced domain wall motion in Pt/GdFeCo wires [1]. By implementing a stroboscopic current-pump, optical-probe scheme synchronized with sub-nanosecond current pulses, we directly visualize domain wall dynamics on sub-nanosecond timescales. The observed motion exhibits a time-dependent velocity, which can be attributed to an enhanced domain wall speed near the angular momentum compensation temperature—a characteristic unique to ferrimagnetic systems.
​ In the second part, I turn to a ferromagnetic Weyl semimetal, Co₃Sn₂S₂, notable for its large Berry curvature. Here, we demonstrate non-volatile magnetization switching induced solely by circularly polarized femtosecond laser pulses, without the need for any applied magnetic field or current [2]. The all-optical magnetization reversal results in a robust and persistent change in the anomalous Hall effect, evidencing a chirality flip of the underlying Weyl fermions. Such optical control enables the creation of arbitrary spatial domain patterns, offering a new platform for studying domain wall physics in magnetic Weyl semimetals [3]. These studies underscore the role of magneto-optical methods as powerful probes of spin texture and dynamics, revealing the potential of light and current to manipulate magnetization in next-generation spintronic systems.
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​ 1. K. Ogawa, N. Yoshikawa, M. Ishibashi, K. Yakushiji, A. Tsukamoto, M. Hayashi and R. Shimano, Phys. Rev. Res. 5, 033151 (2023).
​ 2. N. Yoshikawa†, K. Ogawa†, Y. Hirai, K. Fujiwara, J. Ikeda, A. Tsukazaki and R. Shimano, Commun Phys 5, 1 (2022).
​ 3. ​K. Fujiwara, K. Ogawa, N. Yoshikawa, K. Kobayashi, K. Nomura, R. Shimano and A. Tsukazaki, Commun Mater 5, 1 (2024).
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More information :https://www.spintec.fr/seminar-spin-texture-manipulation-by-current-and-light-probed-via-magneto-optical-microscopy/​

Videoconference ​: https://univ-grenoble-alpes-fr.zoom.us/j/98769867024?pwd=dXNnT3RMeThjYStybGVQSUN0TVdJdz09