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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).

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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