Quantum spin nematic phase in a square-lattice iridate
SCIE
SCOPUS
- Title
- Quantum spin nematic phase in a square-lattice iridate
- Authors
- KIM, BUMJOON; KIM, HOON; KIM, JIN-KWANG; KWON, JUNYOUNG; HA, SEUNGHYEOK; KIM, KWANGRAE; LEE, WONJUN; KIM, JIMIN; KIM, HYUN-WOO; KIM, JONGHWAN; CHO, GIL YOUNG; HEO, HYEOKJUN; JANG, JOONHO; SAHLE, C. J.; LONGO, A.; STREMPFER, J.; FABRRIS, G.; CHOI. Y.; HASKEL, D.; KIM, JUNGHO; KIM, JONG-WOO
- Date Issued
- 2024-01
- Publisher
- Nature Publishing Group
- Abstract
- Spin nematic is a magnetic analogue of classical liquid crystals, a fourth state of matter exhibiting characteristics of both liquid and solid1,2. Particularly intriguing is a valence-bond spin nematic3-5, in which spins are quantum entangled to form a multipolar order without breaking time-reversal symmetry, but its unambiguous experimental realization remains elusive. Here we establish a spin nematic phase in the square-lattice iridate Sr2IrO4, which approximately realizes a pseudospin one-half Heisenberg antiferromagnet in the strong spin-orbit coupling limit6-9. Upon cooling, the transition into the spin nematic phase at TC approximate to 263 K is marked by a divergence in the static spin quadrupole susceptibility extracted from our Raman spectra and concomitant emergence of a collective mode associated with the spontaneous breaking of rotational symmetries. The quadrupolar order persists in the antiferromagnetic phase below TN approximate to 230 K and becomes directly observable through its interference with the antiferromagnetic order in resonant X-ray diffraction, which allows us to uniquely determine its spatial structure. Further, we find using resonant inelastic X-ray scattering a complete breakdown of coherent magnon excitations at short-wavelength scales, suggesting a many-body quantum entanglement in the antiferromagnetic state10,11. Taken together, our results reveal a quantum order underlying the Neel antiferromagnet that is widely believed to be intimately connected to the mechanism of high-temperature superconductivity12,13.
We establish a spin nematic phase in the square-lattice iridate Sr2IrO4 and find a complete breakdown of coherent magnon excitations at short-wavelength scales, suggesting a many-body quantum entanglement in the antiferromagnetic state.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/120919
- DOI
- 10.1038/s41586-023-06829-4
- ISSN
- 0028-0836
- Article Type
- Article
- Citation
- Nature, vol. 625, no. 7994, page. 264 - 269, 2024-01
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