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Refinement of exchange parameters and magnetic form factor of Mn<sub>3</sub>Ir from neutron spectroscopy measurements.

ORAL

Abstract

Inelastic neutron scattering measurements of the fcc kagome antiferromagnet Mn3Ir were performed using the SEQUOIA spectrometer at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). Comparison of the observed magnetic excitations to calculated spin waves, using exchange parameters derived from Density Functional Theory (DFT) calculations1, confirms that 4 exchange parameters are needed to describe the spectra. However the values from DFT underestimate the bandwidth of the excitations. Using these values as initial parameters, fits to the model modified the 2 largest exchange parameters to match the bandwidth. A spin orbit correction to the the magnetic form factor was also provided by the fit. These results are consistent with effective spin orbit coupling mentioned in2. Physically this means the magnetic moment is more extended than the free ion value.
1 L. Szunyogh et al. Phys. Rev B. 79, 020403(R) (2009)
2 H. Chen, Q. Niu, and A. H. MacDonald Phys. Rev. Lett. 112, 017205 (2014)

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Presenters

  • Garrett E Granroth

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

Authors

  • Martin D LeBlanc

    Physics and Astronomy, Memorial University of Newfoundland

  • Adam Aczel

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

  • Garrett E Granroth

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

  • Byron W Southern

    Physics and Astronomy, University of Manitoba

  • Stephen E Nagler

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

  • Jiaqiang Yan

    Materials Science and Engineering, The University of Tennessee, Oak Ridge National Lab, Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge National Lab, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

  • John P. Whitehead

    Physics and Astronomy, Memorial University of Newfoundland

  • Martin Plumer

    Physics and Astronomy, Memorial University of Newfoundland