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Title: Evidence for a spinon Fermi surface in a triangular-lattice quantum-spin-liquid candidate

A quantum spin liquid is an exotic quantum state of matter in which spins are highly entangled and remain disordered down to zero temperature. Such a state of matter is potentially relevant to high-temperature superconductivity and quantum-information applications, and experimental identification of a quantum spin liquid state is of fundamental importance for our understanding of quantum matter. Theoretical studies have proposed various quantum-spin-liquid ground states, most of which are characterized by exotic spin excitations with fractional quantum numbers (termed ‘spinons’). In this paper, we report neutron scattering measurements of the triangular-lattice antiferromagnet YbMgGaO4 that reveal broad spin excitations covering a wide region of the Brillouin zone. The observed diffusive spin excitation persists at the lowest measured energy and shows a clear upper excitation edge, consistent with the particle–hole excitation of a spinon Fermi surface. Finally, our results therefore point to the existence of a quantum spin liquid state with a spinon Fermi surface in YbMgGaO4, which has a perfect spin-1/2 triangular lattice as in the original proposal of quantum spin liquids.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [4] ;  [4] ;  [1] ;  [5] ;  [6] ;  [7] ;  [8] ;  [8] ;  [2] ;  [1] ;  [1]
  1. Fudan Univ., Shanghai (China)
  2. Renmin Univ. of China, Beijing (China)
  3. Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab., ISIS Neutron Source
  4. Inst. Laue-Langevin (ILL), Grenoble (France)
  5. Helmholtz-Zentrum Berlin (HZB), (Germany). German Research Centre for Materials and Energy
  6. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Neutron Research
  7. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  8. China Inst. of Atomic Energy (CIAE), Beijing (China)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; 2016YFA0300203; 2015CB921302; 91421106; 2016YFA0300504
Type:
Accepted Manuscript
Journal Name:
Nature (London)
Additional Journal Information:
Journal Name: Nature (London); Journal Volume: 540; Journal ID: ISSN 0028-0836
Publisher:
Nature Publishing Group
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Fudan Univ., Shanghai (China)
Sponsoring Org:
USDOE Office of Science (SC); National Key R&D Program of the MOST (China); Ministry of Science and Technology (China); National Natural Science Foundation of China (NNSFC)
Contributing Orgs:
Helmholtz-Zentrum Berlin for Materials and Energy, Berlin (Germany); National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); China Inst. of Atomic Energy (CIAE), Beijing (China); Renmin Univ. of China, Beijing (China); Shanghai Jiao Tong Univ. (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China); Inst. Laue-Langevin, Grenoble (France); Science and Technology Facilities Council (STFC), Chilton (United Kingdom)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1335366