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arXiv · 2604.05608

Indication of Stochastic Photothermal Dynamics around a Topological Defect in a Chiral Magnet

Dongxue Han·Asuka Nakamura·Takahiro Shimojima·Kosuke Karube·Yasujiro Taguchi·Yoshinori Tokura·Kyoko Ishizaka
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Abstract

Chiral magnets host topologically protected spin textures whose nonequilibrium dynamics are crucial in phase transitions and domain evolution, yet ultrafast defect-mediated processes remain poorly understood. Here, we investigate photothermally induced helical-to-paramagnetic phase transition in Co$_9$Zn$_9$Mn$_2$ using pump-probe Lorentz transmission electron microscopy (LTEM). Following the suppression of the magnetic stripe contrast induced by femtosecond pulsed laser, we observe a directional recovery process of magnetic order driven by the anisotropic thermal diffusion, toward the thick region that effectively acts as a heat sink. Remarkably, around a magnetic edge dislocation, the magnetic contrast recovery exhibits a pronounced delay accompanied by a transient blurring of LTEM contrast. These findings suggest that the recovery dynamics around the magnetic edge dislocation proceed through multiple relaxation paths that are selected stochastically. Our results indicate a possible enhancement of stochasticity around topological defects during the recovery dynamics of magnetic phase transitions.

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Dongxue Han, Asuka Nakamura, Takahiro Shimojima, Kosuke Karube, Yasujiro Taguchi, Yoshinori Tokura, Kyoko Ishizaka. 2026-04-07. Indication of Stochastic Photothermal Dynamics around a Topological Defect in a Chiral Magnet. https://arxiv.org/abs/2604.05608

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