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, S. -W. Cheong

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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.
Original languageEnglish
Article number134429
Number of pages6
JournalPhysical review B
Issue number13
Publication statusPublished - 22 Oct 2019


  • cond-mat.mtrl-sci
  • cond-mat.str-el


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