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arXiv · 2605.07294

Frustration of harmonic and solitonic helimagnetism on the body-centered tetragonal lattice of GdAlSi

Ryota Nakano·Rinsuke Yamada·Oleg I. Utesov·Masaki Gen·Akiko Kikkawa·Hajime Sagayama·Hironori Nakao·Masashi Tokunaga·Taka-hisa Arima·Yoshinori Tokura·Se Kwon Kim·Max Hirschberger
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Abstract

The triangular lattice antiferromagnet (TLAF) with nearest-neighbor exchange interaction is a model platform in the field of frustrated magnetism. Here, anharmonic (`up-up-down') and harmonic (`120 degree') magnetic states compete, because the fundamental helimagnetic wave and its higher harmonic are degenerate in energy. We show that a body-centered tetragonal lattice (BCTL) can realize a similar frustration of harmonic and anharmonic helimagnetic states, and that the tetragonal magnetic Weyl semimetal GdAlSi realizes this scenario. In an applied magnetic field, resonant elastic X-ray scattering reveals a competition of harmonic cycloidal and solitonic double-Q states, well consistent with mean-field calculations. Our work provides a new paradigm for frustration physics in BCTL materials.

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Ryota Nakano, Rinsuke Yamada, Oleg I. Utesov, Masaki Gen, Akiko Kikkawa, Hajime Sagayama, Hironori Nakao, Masashi Tokunaga, Taka-hisa Arima, Yoshinori Tokura, Se Kwon Kim, Max Hirschberger. 2026-05-08. Frustration of harmonic and solitonic helimagnetism on the body-centered tetragonal lattice of GdAlSi. https://arxiv.org/abs/2605.07294

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