Spin-orbit-entangled Jeff=1/2 magnetism and unconventional spin freezing in the bond-disordered pyrochlore antiferromagnet NaCdCo2F7
Abstract
Bond disorder in frustrated pyrochlore antiferromagnets can give rise to fundamentally different quantum ground states depending on the nature of the local magnetic moments. Here, we show that the bond-disordered Jeff=1/2 pyrochlore antiferromagnet NaCdCo2F7 realizes an unconventional spin-glass-like state with continued dynamics, in stark contrast to its isostructural S=1/2 NaCdCu2F7 counterpart. High-field magnetization and Co L2,3-edge XAS/XMCD establish spin-orbit-entangled Jeff=1/2 Co2+ moments with a substantial unquenched orbital contribution, consistent with local XY anisotropy seen in the isostructural NaA''Co2F7 (A'' = Ca, Sr) analogues. μSR and 23Na NMR measurements reveal progressive slowing of spin fluctuations below ∼10 K, culminating in a partially frozen state with persistent low-temperature dynamics that deviates from a canonical spin glass. Comparison with the isostructural bond-disordered pyrochlore NaCdCu2F7, which realizes a random-singlet state, reveals a fundamentally different response of spin-orbit-entangled Co2+ moments to bond disorder. These results identify spin-orbit coupling as a key ingredient governing the fate of bond-disordered frustrated pyrochlore magnets.
Versions
Related
- Phonon-Programmable Hidden Unconventional Magnetism in Two-Dimensional Spin-Degenerate Antiferromagnets
- Unconventional Mixed-Parity Magnetism in Rare-Earth Tetraborides
- Crystal symmetry predicts unconventional magnetism
- Zeeman quantum geometry as a probe of unconventional magnetism
- Quantum magnetism of the spin-1 kagome-lattice antiferromagnet
BibTeX
@misc{kancko2026spinorbitentangled,
title = {{Spin-orbit-entangled $J_\rm eff=\frac12$ magnetism and unconventional spin freezing in the bond-disordered pyrochlore antiferromagnet NaCdCo$_2$F$_7$}},
author = {Andrej Kancko and Hironori Sakai and Javier Herrero-Martín and Adam Berlie and Marc Uhlarz and Tetiana Haidamak and Milan Klicpera and Yo Tokunaga and Ross H. Colman},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.16875},
eprint = {2606.16875},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.16875},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Spin-orbit-entangled J_eff=1/2 magnetism and unconventional spin freezing in the bond-disordered pyrochlore antiferromagnet NaCdCo_2F_7
AU - Andrej Kancko
AU - Hironori Sakai
AU - Javier Herrero-Martín
AU - Adam Berlie
AU - Marc Uhlarz
AU - Tetiana Haidamak
AU - Milan Klicpera
AU - Yo Tokunaga
AU - Ross H. Colman
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2606.16875
UR - https://arxiv.org/abs/2606.16875
AB - Bond disorder in frustrated pyrochlore antiferromagnets can give rise to fundamentally different quantum ground states depending on the nature of the local magnetic moments. Here, we show that the bond-disordered J_eff=1/2 pyrochlore antiferromagnet NaCdCo_2F_7 realizes an unconventional spin-glass-like state with continued dynamics, in stark contrast to its isostructural S=1/2 NaCdCu_2F_7 counterpart. High-field magnetization and Co L_2,3-edge XAS/XMCD establish spin-orbit-entangled J_eff=1/2 Co^2+ moments with a substantial unquenched orbital contribution, consistent with local XY anisotropy seen in the isostructural NaA''Co_2F_7 (A'' = Ca, Sr) analogues. μSR and ^23Na NMR measurements reveal progressive slowing of spin fluctuations below ∼10 K, culminating in a partially frozen state with persistent low-temperature dynamics that deviates from a canonical spin glass. Comparison with the isostructural bond-disordered pyrochlore NaCdCu_2F_7, which realizes a random-singlet state, reveals a fundamentally different response of spin-orbit-entangled Co^2+ moments to bond disorder. These results identify spin-orbit coupling as a key ingredient governing the fate of bond-disordered frustrated pyrochlore magnets.
ER -