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arXiv · 2508.19675

Ultrafast Spin Accumulations Drive Magnetization Reversal in Multilayers

Harjinder Singh·Alberto Anadón·Junta Igarashi·Quentin Remy·Stéphane Mangin·Michel Hehn·Jon Gorchon·Gregory Malinowski
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Abstract

Engineering and controlling heat and spin transport on the femtosecond time-scale in spintronic devices opens up new ways to manipulate magnetization with unprecedented speed. Yet the underlying reversal mechanisms remain poorly understood due to the challenges of probing ultrafast, non-equilibrium spin dynamics. In this study, we demonstrate that typical magneto-optical experiments can be leveraged to access the time evolution of the spin accumulation generated within a magnetic multilayer following an ultrafast laser excitation. Furthermore, our analysis shows that the final magnetic state of the free-layer in a spin-valve is mainly dictated by the ultrafast dynamics of the reference-layer magnetization. Our results disentangle magnetization and spin transport dynamics within a multilayer stack and identify demagnetization and remagnetization-driven spin accumulation as the key mechanism for all-optical switching. These findings establish new design principles for ultrafast spintronic devices based on tailored spin current engineering.

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Harjinder Singh, Alberto Anadón, Junta Igarashi, Quentin Remy, Stéphane Mangin, Michel Hehn, Jon Gorchon, Gregory Malinowski. 2025-08-27. Ultrafast Spin Accumulations Drive Magnetization Reversal in Multilayers. https://doi.org/10.1103/z2sz-2tdz

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