Published October 9, 2025 | Version Published
Journal Article Open

Possible Observation of Quadrupole Waves in Spin Nematics

  • 1. ROR icon Southern University of Science and Technology
  • 2. ROR icon Great Bay University
  • 3. ROR icon Chinese Academy of Sciences
  • 4. ROR icon University of Chinese Academy of Sciences
  • 5. ROR icon Zhejiang University
  • 6. Shenzhen Institute for Quantum Science and Engineering
  • 7. ROR icon California Institute of Technology
  • 8. ROR icon Australian Nuclear Science and Technology Organisation
  • 9. ROR icon Oak Ridge National Laboratory
  • 10. ROR icon Japan Atomic Energy Agency
  • 11. ROR icon Songshan Lake Materials Laboratory
  • 12. ROR icon Beijing Academy of Quantum Information Sciences
  • 13. ROR icon Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area

Abstract

Discovery of new states of matter is a key objective in modern condensed matter physics, which often leads to revolutionary technological advancements such as superconductivity. Quantum spin nematic, a “hidden order” that evades conventional magnetic probes, is one such state. Na⁢BaNi⁢(PO) is a potential spin nematic material, suggested by the observation of a two-magnon Bose-Einstein condensation from above the saturation field. However, direct confirmation of the spin nematicity remains elusive. This Letter presents inelastic neutron scattering spectra from the putative spin nematic phases of Na⁢BaNi⁢(PO), revealing low-energy quadrupole waves that are absent in the neighboring conventional magnetic phases. A spin-one model quantitatively captures the full details of the spin excitation spectra across all low-temperature phases, providing direct evidence of the spin nematic orders. Additionally, we show evidence of the three-magnon continuum and two-magnon bound states in the 1/3-magnetization plateau, revealing condensation of the two-magnon bound state as the origin of the low-field spin nematic supersolid phase.

Copyright and License

© 2025 American Physical Society.

Acknowledgement

We thank Hai-Qing Lin, Qingming Zhang, Chao Cao, and Ziji Xiang for helpful discussions. This work was supported by the National Key Research and Development Program of China (Grants No. 2021YFA1400400, No. 2021ZD0301800, No. 2022YFA1402200, and No. 2024YFA1408303), the National Natural Science Foundation of China (Grants No. 12134020, No. 12034017, No. 12104255, No. 12322403, No. 12347107, No. 12374124, No. 12374146, No. 12374150, No. 12488201, No. 12494592, and No. 12574157), the Strategic Priority Research Program of Chinese Academy of Sciences (Grants No. XDB0500202 and No. XDB33000000), the Youth Innovation Promotion Association of Chinese Academy of Sciences (Grant No. 2021004), the Key R&D Program of Zhejiang Province, China (Grant No. 2021C01002), the Guangdong Provincial Quantum Science Strategic Initiative (Grants No. GDZX2401006 and No. GDZX2401007), and the Fundamental Research Funds for the Central Universities (Grant No. 226-2024-00068). We also acknowledge the neutron beam time awarded by Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex (J-PARC) through Proposal No. 2024A0351. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory, where the beam time was allocated to CNCS on Proposal No. IPTS-29333.

Data Availability

The data that support the findings of this article are openly available [59].

Supplemental Material

See Supplemental Material for a description of the methods (material systhesis, neutron scattering, iPEPS, LSW, and GLSW) and additional neutron scattering data, which includes Refs. [49-59].

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Additional details

Additional titles

Alternative title
Unveiling the Quadrupole Waves in Spin Nematics

Related works

Is new version of
Discussion Paper: arXiv:2503.13888 (arXiv)
Is supplemented by
Supplemental Material: https://journals.aps.org/prl/supplemental/10.1103/pywx-vxfh/supp.pdf (URL)
Dataset: 10.5061/dryad.zcrjdfnp9 (DOI)

Funding

Ministry of Science and Technology of the People's Republic of China
2021YFA1400400
Ministry of Science and Technology of the People's Republic of China
2021ZD0301800
Ministry of Science and Technology of the People's Republic of China
2022YFA1402200
Ministry of Science and Technology of the People's Republic of China
2024YFA1408303
National Natural Science Foundation of China
12134020
National Natural Science Foundation of China
12034017
National Natural Science Foundation of China
12104255
National Natural Science Foundation of China
12322403
National Natural Science Foundation of China
12347107
National Natural Science Foundation of China
12374124
National Natural Science Foundation of China
12374146
National Natural Science Foundation of China
12374150
National Natural Science Foundation of China
12488201
National Natural Science Foundation of China
12494592
National Natural Science Foundation of China
12574157
Chinese Academy of Sciences
XDB0500202
Chinese Academy of Sciences
XDB33000000
Youth Innovation Promotion Association
2021004
Science and Technology Department of Zhejiang Province
2021C01002
Guangdong Provincial Quantum Science Strategic Initiative
GDZX2401006
Guangdong Provincial Quantum Science Strategic Initiative
GDZX2401007
Ministry of Finance of the People's Republic of China
226-2024-00068
Japan Proton Accelerator Research Complex
2024A0351
United States Department of Energy
IPTS-29333

Dates

Accepted
2025-09-24

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Caltech groups
Division of Chemistry and Chemical Engineering (CCE)
Publication Status
Published