Evidence for a parity broken monoclinic ground state in the S = 1/2 Kagome antiferromagnet Herbertsmithite

ORAL

Abstract

Nearest neighbor interacting S = ½ spins on the ideal Kagomé lattice have been predicted to form a variety of novel quantum entangled states, including quantum spin-liquid (SL) and valence bond solid phases. However, in real materials, the presence of additional perturbative spin interactions may greatly expand the variety of entangled states, which recent theoretical analyses have shown are identifiable through the spontaneous loss of particular discrete point group symmetries. Here we comprehensively resolve the ground state point group symmetries of the prototypical Kagomé SL candidate ZnCu3(OH)6Cl2 (Herbertsmithite) using a combination of optical ellipsometry and wavelength-dependent multi-harmonic optical polarimetry. We uncover a subtle parity breaking monoclinic structural distortion well above the nearest neighbor exchange energy scale. Surprisingly, the parity-breaking order parameter is dramatically enhanced upon cooling and closely tracks the build-up of nearest neighbor spin correlations, suggesting that it is energetically favored by the SL state. The refined low temperature symmetry group greatly restricts the number of viable ground states, and, in the perturbative limit, points toward the formation of a nematic SL ground state, a SL analogue of a liquid crystal.

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Presenters

  • Nicholas Laurita

    • Institute for Quantum Information and Matter, California Institute of Technology
    • Department of Physics, California Institute of Technology

Authors

  • Nicholas Laurita

    • Institute for Quantum Information and Matter, California Institute of Technology
    • Department of Physics, California Institute of Technology

  • Alon Ron

    • Institute for Quantum Information and Matter, California Institute of Technology

  • Jeong Woo Han

    • Department of Physics and Photon Science, Gwangju Institute of Science and Technology

  • Jongseok Lee

    • Department of Physics and Photon Science, Gwangju Institute of Science and Technology
    • Gwangju Institute of Science and Technology

  • Allen Scheie

    • Oak Ridge National Lab
    • Johns Hopkins University
    • Oak Ridge National Laboratory
    • Institute for Quantum Matter, Johns Hopkins University

  • John P Sheckelton

    • Department of Applied Physics, Stanford University

  • Rebecca Smaha

    • Department of Applied Physics, Stanford University

  • Wei He

    • Stanford Univ
    • Department of Materials Science and Engineering, Stanford University
    • Department of Applied Physics, Stanford University

  • Jiajia Wen

    • Stanford Univ
    • Department of Applied Physics, Stanford University
    • SLAC - Natl Accelerator Lab

  • Young Sang Lee

    • Stanford Univ
    • Department of Applied Physics, Stanford University
    • Stanford University

  • Michael Norman

    • Argonne Natl Lab
    • Materials Science Division, Argonne National Laboratory
    • Materials Science Division, Argonne National Lab

  • David Hsieh

    • Institute for Quantum Information and Matter, California Institute of Technology
    • Caltech
    • Department of Physics, California Institute of Technology