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arXiv · 2209.12751

Rhombic skyrmion lattice coupled with orthorhombic structural distortion in EuAl$_{4}$

Masaki Gen·Rina Takagi·Yoshito Watanabe·Shunsuke Kitou·Hajime Sagayama·Naofumi Matsuyama·Yoshimitsu Kohama·Akihiko Ikeda·Yoshichika Ōnuki·Takashi Kurumaji·Taka-hisa Arima·Shinichiro Seki
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Abstract

The centrosymmetric tetragonal itinerant magnet EuAl$_{4}$ exhibits an intricate magnetic phase diagram including rhombic and square skyrmion-lattice (SkL) phases in the external magnetic field. Here, we report a multi-axis dilatometric investigation of EuAl$_{4}$ by means of a newly designed fiber-Bragg-grating technique complemented by a resonant x-ray scattering experiment, revealing anisotropic magnetostriction and magnetovolume effect associated with successive phase transitions. The rhombic and square SkL phases are found to possess $\sim$0.10% and $\sim$0.03% orthorhombic structural distortion within the $ab$ plane, respectively. We propose that the coupling between the spin system and the lattice deformation should be essential for the structural instability in EuAl$_{4}$, yielding a rich variety of topological spin textures with spontaneous rotational-symmetry breaking as well as a potential controllability of the SkL phases by uniaxial stress or pressure.

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Masaki Gen, Rina Takagi, Yoshito Watanabe, Shunsuke Kitou, Hajime Sagayama, Naofumi Matsuyama, Yoshimitsu Kohama, Akihiko Ikeda, Yoshichika Ōnuki, Takashi Kurumaji, Taka-hisa Arima, Shinichiro Seki. 2022-09-26. Rhombic skyrmion lattice coupled with orthorhombic structural distortion in EuAl$_{4}$. https://doi.org/10.1103/physrevb.107.l020410

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