Cluster Frustration in the Breathing Pyrochlore Magnet LiGaCr<sub>4</sub>S<sub>8</sub>

ORAL

Abstract

We present a comprehensive neutron scattering study of the breathing pyrochlore magnet LiGaCr4S8 [1]. We observe an unconventional magnetic excitation spectrum with a separation of high- and low-energy spin dynamics above a spin-freezing transition at 12(2) K. By fitting to magnetic diffuse-scattering data, we parametrize the spin Hamiltonian. Interactions are ferromagnetic within tetrahedra of the breathing pyrochlore lattice, but antiferromagnetic further-neighbor interactions are also essential to explain our data, in qualitative agreement with density-functional-theory predictions [2]. We explain the origin of geometrical frustration in LiGaCr4S8 in terms of net antiferromagnetic coupling between emergent tetrahedral spin clusters that occupy a face-centered-cubic lattice. Our results provide insight into the emergence of frustration in the presence of strong further-neighbor couplings, and a blueprint for determining magnetic interactions in classical spin liquids.
[1] Pokharel et al., Phys. Rev. Lett. 125, 167201 (2020).
[2] Ghosh et al., npj Quantum Mater. 4, 63 (2019).

*U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division; Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant GBMF4416 (G.P. and H.S.A.).

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Presenters

  • Joseph Paddison

    • Oak Ridge National Lab
    • Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
    • Oak Ridge National Laboratory

Authors

  • Joseph Paddison

    • Oak Ridge National Lab
    • Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
    • Oak Ridge National Laboratory

  • Ganesh Pokharel

    • Department of Physics, University of Tennessee Knoxville
    • Department of Physics & Astronomy, University of Tennessee, Knoxville, TN 37996, USA
    • University of Tennessee - Knoxville

  • Hasitha Suriya Arachchige

    • Department of Physics & Astronomy, University of Tennessee, Knoxville, TN 37996, USA
    • University of Tennessee - Knoxville
    • Department of Materials Science, The University of Tennessee

  • Travis Williams

    • Oak Ridge National Lab
    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory

  • Andrew May

    • Oak Ridge National Laboratory
    • Oak Ridge National Lab
    • Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

  • Randy Fishman

    • Oak Ridge National Lab
    • Oak Ridge National Laboratory

  • Gabriele Sala

    • Oak Ridge National Lab
    • Oak Ridge National Laboratory

  • Stuart Calder

    • Oak Ridge National Laboratory
    • Oak Ridge National Lab
    • Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

  • Georg Ehlers

    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Oak Ridge National Lab
    • Oak Ridge National Laboratory

  • David Parker

    • Oak Ridge National Lab
    • Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

  • Tao Hong

    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory
    • Oak Ridge National Lab

  • Andrew R Wildes

    • Institut Laue-Langevin
    • Institut Laue Langevin

  • David George Mandrus

    • Materials Science and Technology Division, Oak Ridge National Labratory
    • Materials Science and Engineering, University of Tennessee
    • Department of Materials Science and Engineering, University of Tennessee
    • University of Tennessee
    • Department of Materials Science and Engineering, University of Tennessee Knoxville
    • Department of Materials Science & Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
    • Oakridge National Laboratory
    • Materials Science and Engineering, University of Tennessee, Knoxville
    • Oak Ridge National Laboratory
    • University of Tennessee - Knoxville
    • Materials Science and Technology Division, Oak Ridge National Laboratory
    • Department of Physics, University of Tennessee Knoxville
    • Materials Science and Technology, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory, Materials Science and Technology Division
    • Department of Materials Science, The University of Tennessee
    • University of Tennessee, Knoxville

  • Andrew Christianson

    • Oak Ridge National Lab
    • Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
    • Oak Ridge National Laboratory