Kagome lattice candidate URhSn: Measured Bragg diffraction patterns and theory for hexagonal and trigonal Sohncke phases
Abstract
Ternary intermetallics use a ZrNiAl-type chemical structure known as a kagome system. Complexity observed in the phase diagrams of these compounds is attributed to the geometric frustration. The 5f-electron compound URhSn exhibits two phase transitions at 16 K and 54 K. No super-lattice reflections in neutron powder diffraction patterns are detected in the intermediate range of temperatures (16 K - 54 K). Recent resonant x-ray diffraction patterns for uranium ions in the intermediate phase suggest a chiral structure and a trigonal Sohncke space group. It is firmly established that a simple hexagonal space group describes the parent structure at room temperature. A ferroic order parameter that includes hexadecapoles is shown to characterize the trigonal Sohncke phase. Resonant x-ray diffraction by this phase is fully investigated with our symmetry informed theory. It repairs symmetry in the original data analysis by using a grey group, and it lifts an unjustified spatial condition on uranium positions. The theory uses axial atomic multipoles that satisfy sum-rules established in the first instance for x-ray dichroic signals. A confrontation between observed and calculated diffraction patterns lends support to a trigonal Sohncke phase, and exposes grounds for additional experimental work on an enigmatic compound.
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BibTeX
@misc{lovesey2026kagome,
title = {{Kagome lattice candidate URhSn: Measured Bragg diffraction patterns and theory for hexagonal and trigonal Sohncke phases}},
author = {S. W. Lovesey and D. D. Khalyavin},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.14429},
eprint = {2609.14429},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.14429},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Kagome lattice candidate URhSn: Measured Bragg diffraction patterns and theory for hexagonal and trigonal Sohncke phases
AU - S. W. Lovesey
AU - D. D. Khalyavin
PY - 2026
DA - 2026/09/13
PB - arXiv
DO - 10.48550/arxiv.2609.14429
UR - https://arxiv.org/abs/2609.14429
AB - Ternary intermetallics use a ZrNiAl-type chemical structure known as a kagome system. Complexity observed in the phase diagrams of these compounds is attributed to the geometric frustration. The 5f-electron compound URhSn exhibits two phase transitions at 16 K and 54 K. No super-lattice reflections in neutron powder diffraction patterns are detected in the intermediate range of temperatures (16 K - 54 K). Recent resonant x-ray diffraction patterns for uranium ions in the intermediate phase suggest a chiral structure and a trigonal Sohncke space group. It is firmly established that a simple hexagonal space group describes the parent structure at room temperature. A ferroic order parameter that includes hexadecapoles is shown to characterize the trigonal Sohncke phase. Resonant x-ray diffraction by this phase is fully investigated with our symmetry informed theory. It repairs symmetry in the original data analysis by using a grey group, and it lifts an unjustified spatial condition on uranium positions. The theory uses axial atomic multipoles that satisfy sum-rules established in the first instance for x-ray dichroic signals. A confrontation between observed and calculated diffraction patterns lends support to a trigonal Sohncke phase, and exposes grounds for additional experimental work on an enigmatic compound.
ER -