Helical-to-Fan Transitions under Magnetic Fields in the Noncentrosymmetric Tetragonal Magnet EuRhGe3
Abstract
The magnetic structure of EuRhGe3, a noncentrosymmetric body-centered tetragonal magnet with the space group I4mm, has been investigated by resonant X-ray diffraction. Below TN=12 K, EuRhGe3 undergoes a helical magnetic ordering with an incommensurate propagation vector q=(0, 0, 0.809), in which the magnetic moments lie in the ab plane and rotate by a constant turn angle of 145.8∘ between adjacent layers. When a magnetic field is applied along the a axis at 2 K, a second-harmonic 2q peak develops, indicating that the circular helix is gradually distorted into a helimagnetic soliton-lattice state, which eventually undergoes a lock-in transition to the commensurate structure with q=0.8 at 3.8 T. Above the subsequent phase boundary at 5 T, the helicity is lost, and a spin-flop xyz-fan (elliptic conical) state is realized, in which the moments oscillate predominantly along the b axis but are accompanied by a small c-axis component. At higher fields, the system enters a conventional planar xy-fan phase without a c-axis component. EuRhGe3 provides a prototypical example of a helimagnet that exhibits a full sequence of field-induced structures, evolving from a circular helix to a spin-flop xyz-fan (elliptic conical), and finally to a planar xy-fan structure, which has been theoretically predicted.
Versions
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BibTeX
@misc{matsumura2026helicaltofan,
title = {{Helical-to-Fan Transitions under Magnetic Fields in the Noncentrosymmetric Tetragonal Magnet EuRhGe$_3$}},
author = {Takeshi Matsumura and Hiroto Nitta and Hironori Nakao and Masashi Kakihana and Masato Hedo and Takao Nakama and Yoshichika Ōnuki},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.05709},
eprint = {2608.05709},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.05709},
}
RIS
TY - UNPB
TI - Helical-to-Fan Transitions under Magnetic Fields in the Noncentrosymmetric Tetragonal Magnet EuRhGe_3
AU - Takeshi Matsumura
AU - Hiroto Nitta
AU - Hironori Nakao
AU - Masashi Kakihana
AU - Masato Hedo
AU - Takao Nakama
AU - Yoshichika Ōnuki
PY - 2026
DA - 2026/08/06
PB - arXiv
DO - 10.48550/arxiv.2608.05709
UR - https://arxiv.org/abs/2608.05709
AB - The magnetic structure of EuRhGe_3, a noncentrosymmetric body-centered tetragonal magnet with the space group I4mm, has been investigated by resonant X-ray diffraction. Below T_N=12 K, EuRhGe_3 undergoes a helical magnetic ordering with an incommensurate propagation vector q=(0, 0, 0.809), in which the magnetic moments lie in the ab plane and rotate by a constant turn angle of 145.8^∘ between adjacent layers. When a magnetic field is applied along the a axis at 2 K, a second-harmonic 2q peak develops, indicating that the circular helix is gradually distorted into a helimagnetic soliton-lattice state, which eventually undergoes a lock-in transition to the commensurate structure with q=0.8 at 3.8 T. Above the subsequent phase boundary at 5 T, the helicity is lost, and a spin-flop xyz-fan (elliptic conical) state is realized, in which the moments oscillate predominantly along the b axis but are accompanied by a small c-axis component. At higher fields, the system enters a conventional planar xy-fan phase without a c-axis component. EuRhGe_3 provides a prototypical example of a helimagnet that exhibits a full sequence of field-induced structures, evolving from a circular helix to a spin-flop xyz-fan (elliptic conical), and finally to a planar xy-fan structure, which has been theoretically predicted.
ER -