Magnetic excitations of the classical spin-liquid MgCr<sub>2</sub>O<sub>4</sub>

ORAL

Abstract

We report a comprehensive inelastic neutron-scattering study of the frustrated pyrochlore antiferromagnet MgCr2O4 in its cooperative paramagnetic regime. Theoretical modeling yields a microscopic Heisenberg model with exchange interactions up to third-nearest neighbors, which quantitatively explains all the details of the dynamic magnetic response. Our work demonstrates that the magnetic excitations in MgCr2O4 are faithfully represented in the entire Brillouin zone by a theory of magnon excitations propagating in a highly-correlated paramagnetic background. Our results also suggest that MgCr2O4 is proximate to a spiral spin-liquid phase distinct from the Coulomb phase, what has implications for the magneto-structural phase transition observed at low temperature in this material.

*This was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under awards number DE-SC-0018660 and DE-FG02-08ER46544.

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Presenters

  • Andrei T Savici

    • ORNL
    • Oak Ridge National Lab

Authors

  • Martin Mourigal

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

  • Xiaojian Bai

    • School of Physics, Georgia Institute of Technology
    • Georgia Institute of Technology

  • Joseph Paddison

    • Churchill College, University of Cambridge
    • Cambridge
    • University of Cambridge
    • Georgia Institute of Technology
    • Univserity of Cambridge
    • Department of Physics, University of Cambridge

  • Eliot Kapit

    • Mines
    • Colorado Sch of Mines
    • physics, colorado school of mines
    • Colorado School of Mines
    • Physics, Colorado School of Mines

  • Seyed Koohpayeh

    • Johns Hopkins
    • Johns Hopkins University
    • Institute for Quantum Matter, Johns Hopkins University
    • Henry A. Rowland Department of Physics and Astronomy, Johns Hopkins University

  • Jiajia Wen

    • SLAC
    • Department of Applied Physics, Stanford University

  • Sian E Dutton

    • Cambridge

  • Collin Broholm

    • Johns Hopkins
    • Johns Hopkins University
    • IQM, Johns Hopkins University
    • Department of Physics and Astronomy, Johns Hopkins University

  • John Chalker

    • Oxford

  • Andrei T Savici

    • ORNL
    • Oak Ridge National Lab

  • Garrett E Granroth

    • Oak Ridge National Laboratory
    • ORNL

  • Alexander I Kolesnikov

    • ORNL
    • Oak Ridge National Laboratory
    • Spallation Neutron Source, Oak Ridge National Laboratory