Hierarchy of exchange interactions in the triangular-lattice spin-liquid YbMgGaO4

ORAL

Abstract

The spin-1/2 triangular lattice antiferromagnet YbMgGaO4 has attracted recent attention as a quantum spin-liquid candidate. Whether a quantum spin-liquid is stabilized or not depends on the interplay of various exchange interactions with chemical disorder that is inherent to the layered structure of the compound. We combine time-domain terahertz spectroscopy and inelastic neutron scattering measurements in the field polarized state of YbMgGaO4 to obtain better microscopic insights on its exchange interactions. Terahertz spectroscopy in this fashion probes the spin-wave excitations at the Brillouin zone center, ideally complementing neutron scattering. A global spin-wave fit to all our spectroscopic data at fields over 4 T, informed by the analysis of the terahertz spectroscopy linewidths, yields stringent constraints on g-factors and exchange interactions. Our results paint YbMgGaO4 as an easy-plane XXZ antiferromagnet with the combined and necessary presence of sub-leading next nearest neighbor and weak anisotropic off-diagonal nearest-neighbor interactions. This work establishes the hierarchy of exchange interactions in YbMgGaO4 and thus strongly constrains possible mechanisms responsible for the observed spin-liquid phenomenology.

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Presenters

  • Xinshu Zhang

    Johns Hopkins Univ

Authors

  • Xinshu Zhang

    Johns Hopkins Univ

  • Fahad Mahmood

    Department of Physics and Astronomy, The Johns Hopkins University, Johns Hopkins University, Johns Hopkins Univ

  • Marcus Daum

    School of Physics, Georgia Institute of Technology, School of Physics, Georgia Tech

  • Zhiling Dun

    Department of Physics and Astronomy, University of Tennessee, School of Physics, Georgia Institute of Technology, School of Physics, Georgia Tech, Georgia Institute of Technology, Physics, Georgia Institute of Technology, Physics, Georgia Inst of Tech

  • Joseph Paddison

    School of Physics, Georgia Institute of Technology, University of Cambridge, Physics, Georgia Inst of Tech, Physics, University of Cambridge

  • Nicholas Laurita

    Department of Physics and Astronomy, Johns Hopkins Unversity, Johns Hopkins Univ, Johns Hopkins University, Institute For Quantum Information and Matter, California Institute of Technology

  • Tao Hong

    Neutron Scattering Division, Oak Ridge National Laboratory, Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge National Lab, Oak Ridge National Laboratory, Neutron scattering devision, Oak Ridge National Lab

  • Haidong Zhou

    Physics and Astronomy, Univ of Tennessee, Knoxville, Physics and Astronomy, University of Tennessee Knoxville, Department of Physics and Astronomy, University of Tennessee, Department of Physics and Astronomy, University of Tennessee Knoxville, Department of Physics & Astronomy, University of Tennessee, University of Tennessee, Physics and Astronomy, University of Tennessee, Physics, University of Tennessee, Univ of Tennessee, Knoxville, Physics and Astronomy, University of Tennessee, knoxville, Dept. of Physics and Astronomy, University of Tennessee

  • Peter Armitage

    Department of Physics and Astronomy, The Johns Hopkins University, Department of Physics and Astronomy, Johns Hopkins Unversity, Johns Hopkins University, Johns Hopkins Univ, Institute for Quantum Matter, Johns Hopkins University, The Johns Hopkins University

  • Martin Mourigal

    School of Physics, Georgia Inst of Tech, School of Physics, Georgia Institute of Technology, School of Physics, Georgia Tech, Georgia Inst of Tech, Georgia Institute of Technology, Physics, Georgia Inst of Tech