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Title: Continuous excitations of the triangular-lattice quantum spin liquid YbMgGaO 4

A quantum spin liquid (QSL) is an exotic state of matter in which electrons’ spins are quantum entangled over long distances, but do not show magnetic order in the zero-temperature limit. The observation of QSL states is a central aim of experimental physics, because they host collective excitations that transcend our knowledge of quantum matter; however, examples in real materials are scarce. We report neutron-scattering experiments on YbMgGaO 4, a QSL candidate in which Yb 3+ ions with effective spin-1/2 occupy a triangular lattice. Furthermore, our measurements reveal a continuum of magnetic excitations—the essential experimental hallmark of a QSL7—at very low temperature (0.06 K). The origin of this peculiar excitation spectrum is a crucial question, because isotropic nearest-neighbour interactions do not yield a QSL ground state on the triangular lattice. In using measurements the field-polarized state, we identify antiferromagnetic next-nearest-neighbour interactions spin-space anisotropies and chemical disorder between the magnetic layers as key ingredients in YbMgGaO 4.
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [2] ;  [1]
  1. Georgia Inst. of Technology, Atlanta, GA (United States). School of Physics
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nature Physics
Additional Journal Information:
Journal Volume: 13; Journal Issue: 2; Journal ID: ISSN 1745-2473
Nature Publishing Group (NPG)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; electronic properties and materials; magnetic properties and materials; quantum fluids and solids
OSTI Identifier: