The bixbyite framework as a platform for frustrated noncollinear magnetism: resolving the magnetic ground state of β-Fe2O3
Abstract
Magnetic behavior across Fe2O3 polymorphs varies widely despite identical chemistry, highlighting crystal architecture as a key determinant of exchange topology, magnetic anisotropy, and ultimately magnetic order. Here, using neutron and synchrotron X-ray diffraction, we establish the magnetic ground state of the poorly understood bixbyite β-Fe2O3 polymorph and uncover the structural origin of its strong frustration. Below the Néel temperature, a noncollinear antiferromagnetic state emerges through activation of the mH1+ irrep at the H-point [k=(1,1,1)] and the antitranslation (1'|1/2,1/2,1/2), breaking the body centering and yielding two interpenetrating primitive cubic magnetic subcells with inverted moments and nonpolar type-IV symmetry. Under exclusively antiferromagnetic Fe3+-O-Fe3+ interactions, β-Fe2O3 exhibits a large frustration index (f ≈ 7.56). This behavior originates from the intrinsic geometry of the bixbyite lattice: two magnetic sublattices with distinct point symmetries and anisotropy constraints are embedded in a three-dimensional exchange network containing interconnected triangular and hexagonal motifs. In {111} planes, Fe2 ions form hexagonal rings interconnected by frustrated triangular units, while locally Ising-like Fe1 ions occupy the ring centers. Our results thus identify the bixbyite architecture as a promising general platform for frustrated noncollinear magnetism. Extending this structural framework to other magnetic transition-metal or 4f ions opens a materials space for engineering competing exchange interactions and anisotropies, potentially stabilizing new noncollinear and field-tunable magnetic states.
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BibTeX
@misc{tang2026bixbyite,
title = {{The bixbyite framework as a platform for frustrated noncollinear magnetism: resolving the magnetic ground state of $β$-Fe$_2$O$_3$}},
author = {Chenjun Tang and Ondřej Malina and Jiři Tuček and Francois Fauth and Marti Gich and Jose Luis Garcia-Muñoz},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2606.17842},
eprint = {2606.17842},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.17842},
}
RIS
TY - UNPB
TI - The bixbyite framework as a platform for frustrated noncollinear magnetism: resolving the magnetic ground state of β-Fe_2O_3
AU - Chenjun Tang
AU - Ondřej Malina
AU - Jiři Tuček
AU - Francois Fauth
AU - Marti Gich
AU - Jose Luis Garcia-Muñoz
PY - 2026
DA - 2026/08/28
PB - arXiv
DO - 10.48550/arxiv.2606.17842
UR - https://arxiv.org/abs/2606.17842
AB - Magnetic behavior across Fe_2O_3 polymorphs varies widely despite identical chemistry, highlighting crystal architecture as a key determinant of exchange topology, magnetic anisotropy, and ultimately magnetic order. Here, using neutron and synchrotron X-ray diffraction, we establish the magnetic ground state of the poorly understood bixbyite β-Fe_2O_3 polymorph and uncover the structural origin of its strong frustration. Below the Néel temperature, a noncollinear antiferromagnetic state emerges through activation of the mH_1^+ irrep at the H-point [k=(1,1,1)] and the antitranslation (1'|1/2,1/2,1/2), breaking the body centering and yielding two interpenetrating primitive cubic magnetic subcells with inverted moments and nonpolar type-IV symmetry. Under exclusively antiferromagnetic Fe^3+-O-Fe^3+ interactions, β-Fe_2O_3 exhibits a large frustration index (f ≈ 7.56). This behavior originates from the intrinsic geometry of the bixbyite lattice: two magnetic sublattices with distinct point symmetries and anisotropy constraints are embedded in a three-dimensional exchange network containing interconnected triangular and hexagonal motifs. In {111} planes, Fe2 ions form hexagonal rings interconnected by frustrated triangular units, while locally Ising-like Fe1 ions occupy the ring centers. Our results thus identify the bixbyite architecture as a promising general platform for frustrated noncollinear magnetism. Extending this structural framework to other magnetic transition-metal or 4f ions opens a materials space for engineering competing exchange interactions and anisotropies, potentially stabilizing new noncollinear and field-tunable magnetic states.
ER -