Magnetoelastic coupling in Ba3CoSb2O9

ORAL

Abstract

In a variety of frustrated triangular lattice antiferromagnets (TLAF) with easy-plane anisotropy, it has been shown that a magnetization plateau is produced at 1/3 of the saturation value for a magnetic field in the basal plane. This magnetization plateau is associated with a collinear up-up-down state where two spins are parallel to the field while the third one is antiparallel. So far, this plateau has been shown to be accounted for by quantum and thermal fluctuations. In a classical model, quantum fluctuations can be taken into account using a bi-quadratic coupling (~S4), responsible for the magnetization plateau in TLAF, which can also be associated with magnetoelastic effects. For triangular lattices with weak interlayer interaction and an effective 1/2 spin, Ba3CoSb2O9 is a frustrated quantum system. In order to determine the magnitude of bi-quadratic coupling, we estimated the magnetoelastic coupling strength by measuring the relative ultrasound velocity variation as a function of the field orientation at constant temperatures and field values. By analyzing the experimental results in paramagnetic and ordered states, which are significantly different, we can conclude that the magnetoelastic coupling in Ba3CoSb2O9 is large enough to stabilize the collinear up-up-down state.

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Presenters

  • Ming Li

    Department of Physics and Physical Oceanography, Memorial University of Newfoundland

Authors

  • Ming Li

    Department of Physics and Physical Oceanography, Memorial University of Newfoundland

  • Guy Quirion

    Department of Physics and Physical Oceanography, Memorial University of Newfoundland, Physics and Physical Oceanography, Memo Univ of Newfoundland

  • Martin Plumer

    Department of Physics and Physical Oceanography, Memorial University of Newfoundland

  • Jeffrey Quilliam

    Physics Department, Sherbrooke University, Département de Physique et Institut Quantique, Université de Sherbrooke, University of Sherbrooke

  • 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

  • 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