Fitting crystal field excitations using point-charge model -- application to rare earth pyrochlore, Kagome, and triangular magnets

ORAL

Abstract

Determining the single ion crystal field (CF) Hamiltonian is usually an indispensable step to understand the collective low-temperature magnetism in rare earth magnets. This sometimes becomes challenging in low-symmetry systems due to the limited experimental observables compared to a large number of fitted CF parameters. Here I describe a general method to fit neutron CF excitation spectrum using point charge models. By benchmarking with the existing inelastic neutron scattering measurements of pyrochlore oxides (R2X2O7), we achieve a simple and universal point-charge model. This model is then modified and applied to the newly discovered tripod Kagome magnets (R2Mg2Sb3O14), through which the principal axes and local g-tensor in the pseudo-spin basis can be determined and diagonalized. Finally, we apply the point-charge calculation to the triangular lattice magnet YbMgGaO4 and relates its mysterious extra CF levels to the local structure disorder.

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Presenters

  • Zhiling Dun

    School of Physics, Georgia Institute of Technology, Georgia Institute of Technology, School of Physics, Georgia Tech, University of Tennessee, Department of Physics, University of Tennessee

Authors

  • Zhiling Dun

    School of Physics, Georgia Institute of Technology, Georgia Institute of Technology, School of Physics, Georgia Tech, University of Tennessee, Department of Physics, University of Tennessee

  • 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

  • Matthew Brandon Stone

    Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge National Laboratory, Oak Ridge National Lab, Spallation Neutron Source, Oak Ridge National Laboratory

  • Haidong Zhou

    University of Tennessee, Department of Physics and Astronomy, University of Tennessee, University of Tennessee, Knoxville, Physics, University of Tennessee, Knoxville, TN, United States, Physics, University of Tennessee, Department of Physics and Astronomy, The University of Tennessee, Knoxville, Department of Physics and Astronomy, University of Tennessee, Knoxville, Department of Physics, University of Tennessee

  • Martin Mourigal

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