Magnon-polaron excitations in the noncollinear antiferromagnet Mn3Ge

A. S. Sukhanov, M. S. Pavlovskii, Ph. Bourges, H. C. Walker, K. Manna, C. Felser, and D. S. Inosov
Phys. Rev. B 99, 214445 – Published 28 June 2019

Abstract

We present detailed inelastic neutron scattering measurements of the noncollinear antiferromagnet Mn3Ge. Time-of-flight and triple-axis spectroscopy experiments were conducted at the temperature of 6 K, well below the high magnetic ordering temperature of 370 K. The magnetic excitations have a 5-meV gap and display an anisotropic dispersive mode reaching 90 meV at the boundaries of the magnetic Brillouin zone. The spectrum at the zone center shows two additional excitations that demonstrate characteristics of both magnons and phonons. Ab initio lattice-dynamics calculations show that these can be associated with the magnon-polaron modes resulting from the hybridization of the spin fluctuations and the low-energy optical phonons. The observed magnetoelastic coupling agrees with the previously found negative thermal expansion in this compound and resembles the features reported in the spectroscopic studies of other antiferromagnets with similar noncollinear spin structures.

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  • Received 8 April 2019
  • Revised 1 June 2019

DOI:https://doi.org/10.1103/PhysRevB.99.214445

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

A. S. Sukhanov1,2,*, M. S. Pavlovskii3, Ph. Bourges4, H. C. Walker5, K. Manna1, C. Felser1, and D. S. Inosov2

  • 1Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
  • 2Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01069 Dresden, Germany
  • 3Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russian Federation
  • 4Laboratoire Léon Brillouin, CEA-CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France
  • 5ISIS Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11-0QX, United Kingdom

  • *alexandr.sukhanov@cpfs.mpg.de

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Issue

Vol. 99, Iss. 21 — 1 June 2019

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