Spin-wave directional anisotropies in antiferromagnetic Ba3NbFe3Si2O14

Journal article

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.

Authors: Stock, C; Johnson, R; Giles-Donovan, N; Songvilay, M; Rodriguez-Rivera, J

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review B
• Volume: 100
• Issue: 13
• Article number: 134429
• Publication date: 2019-10-22
• Acceptance date: 2019-10-07
• DOI: 10.1103/PhysRevB.100.134429
• EISSN: 2469-9969
• ISSN: 2469-9950
• Keywords: FFR