Spin-wave directional anisotropies in antiferromagnetic Ba3NbFe3Si2O14

C. Stock, R. D. Johnson, N. Giles-Donovan, M. Songvilay, J. A. Rodriguez-Rivera, N. Lee, X. Xu, P. G. Radaelli, L. C. Chapon, A. Bombardi, S. Cochran, Ch. Niedermayer, A. Schneidewind, Z. Husges, Z. Lu, S. Meng, and S.-W. Cheong
Phys. Rev. B 100, 134429 – Published 22 October 2019

Abstract

Ba3NbFe3Si2O14 (langasite) is structurally and magnetically single-domain chiral with the magnetic helicity induced through competing symmetric exchange interactions. Using neutron scattering, we show that the spin waves in antiferromagnetic langasite display directional anisotropy. On applying a time-reversal symmetry breaking magnetic field along the c axis, the spin-wave energies differ when the sign is reversed for either the momentum transfer ±Q or applied magnetic field ±μ0H. When the field is applied within the crystallographic ab plane, the spin-wave dispersion is directionally isotropic and symmetric in ±μ0H. However, a directional anisotropy is observed in the spin-wave intensity. We discuss this directional anisotropy in the dispersion in langasite in terms of a field-induced precession of the dynamic unit cell staggered magnetization resulting from a broken twofold symmetry. Directional anisotropy, often referred to as nonreciprocal responses, can occur in antiferromagnetic phases in the absence of the Dzyaloshinskii-Moriya interaction or other effects resulting from spin-orbit coupling.

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  • Received 20 June 2019
  • Revised 30 August 2019

DOI:https://doi.org/10.1103/PhysRevB.100.134429

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

C. Stock1, R. D. Johnson2, N. Giles-Donovan3, M. Songvilay1, J. A. Rodriguez-Rivera4,5, N. Lee6, X. Xu6, P. G. Radaelli2, L. C. Chapon7, A. Bombardi7, S. Cochran3, Ch. Niedermayer8, A. Schneidewind9,10, Z. Husges11, Z. Lu11, S. Meng11, and S.-W. Cheong6

  • 1School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
  • 2Oxford Physics, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kindom
  • 3Medical and Industrial Ultrasonics, School of Engineering, University of Glasgow G128QQ, United Kingdom
  • 4NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
  • 5Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
  • 6Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
  • 7Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
  • 8Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
  • 9Forschungsneutronenquell Heinz Meier-Leibnitz (FRM-II), D-85747 Garching, Germany
  • 10Institut fur Festkorperphysiki, TU Dresden, D-1062 Dresden, Germany
  • 11Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany

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Issue

Vol. 100, Iss. 13 — 1 October 2019

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