Hidden Triakontadipole Order in the Triangular-Lattice Magnet CeMgAl11O19
Abstract
The absence of magnetic Bragg peaks and a broad excitation continuum are commonly recognized experimental features of a quantum spin liquid. The Ce-based triangular-lattice hexaaluminate CeMgAl11O19 exhibits both signatures, yet its effective model and ground state remain under debate. Experiments have variously suggested a quantum spin liquid, proximate umbrella point, and disorder-suppressed magnetic order. Here we trace these contradictions to an overlooked multipolar degree of freedom: the transverse pseudospin of the |±5/2⟩ Kramers doublet is a rank-5 triakontadipole rather than an ordinary dipole. Analyzing the magnetization, neutron spectra, and thermodynamics on equal footing, we establish a dipole-triakontadipole XXZ model with J⊥ ≃ 0.65 K and Jc ≃ −0.13 K. The resulting planar triakontadipolar superfluid order is hidden from dipolar probes, explaining the absence of a magnetic Bragg peak in neutron scattering. The zero-field excitations separate into a low-energy triakontadipole wave and a broad higher-energy continuum. We further propose nuclear spin-lattice relaxation and spin-current experiments to probe the gapless excitations of this hidden triakontadipole superfluid. Our findings thus open a new avenue for high-rank multipolar physics in rare-earth triangular-lattice magnets.
Related
- Chiral enhancement of two-magnon bound states in an S=1/2 triangular-lattice magnet
- A continuous confinement-deconfinement transition in a triangular quantum magnet
- Ab initio spin Hamiltonians and magnetism of Ce and Yb triangular-lattice compounds
- Observation of Magnetic-Anisotropy Crossover and High-Temperature Skyrmions in the Dirac Magnet Fe3Ge with a Distorted Kagome Lattice
- Compass Correlations in a Square-Lattice Magnet
BibTeX
@misc{liu2026hidden,
title = {{Hidden Triakontadipole Order in the Triangular-Lattice Magnet CeMgAl$_11$O$_19$}},
author = {Yu-Bo Liu and Yuan Gao and Zhen Ma and Shufan Cheng and Xinyang Liu and Jinsheng Wen and Wei Li},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.04845},
eprint = {2611.04845},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.04845},
}
RIS
TY - UNPB
TI - Hidden Triakontadipole Order in the Triangular-Lattice Magnet CeMgAl_11O_19
AU - Yu-Bo Liu
AU - Yuan Gao
AU - Zhen Ma
AU - Shufan Cheng
AU - Xinyang Liu
AU - Jinsheng Wen
AU - Wei Li
PY - 2026
DA - 2026/11/03
PB - arXiv
DO - 10.48550/arxiv.2611.04845
UR - https://arxiv.org/abs/2611.04845
AB - The absence of magnetic Bragg peaks and a broad excitation continuum are commonly recognized experimental features of a quantum spin liquid. The Ce-based triangular-lattice hexaaluminate CeMgAl_11O_19 exhibits both signatures, yet its effective model and ground state remain under debate. Experiments have variously suggested a quantum spin liquid, proximate umbrella point, and disorder-suppressed magnetic order. Here we trace these contradictions to an overlooked multipolar degree of freedom: the transverse pseudospin of the |±5/2⟩ Kramers doublet is a rank-5 triakontadipole rather than an ordinary dipole. Analyzing the magnetization, neutron spectra, and thermodynamics on equal footing, we establish a dipole-triakontadipole XXZ model with J_⊥ ≃ 0.65 K and J_c ≃ −0.13 K. The resulting planar triakontadipolar superfluid order is hidden from dipolar probes, explaining the absence of a magnetic Bragg peak in neutron scattering. The zero-field excitations separate into a low-energy triakontadipole wave and a broad higher-energy continuum. We further propose nuclear spin-lattice relaxation and spin-current experiments to probe the gapless excitations of this hidden triakontadipole superfluid. Our findings thus open a new avenue for high-rank multipolar physics in rare-earth triangular-lattice magnets.
ER -