Field dependence of the NMR frequency in BaFe12O19

The field dependence of the NMR frequencies for the “a” and “c” sites of BaFe₁₂O₁₉ has been re-examined. In a polycrystalline grain-oriented sample at 4.2 K no indication for a deviation from the antiparallel orientation of the sublattice magnetization is found. For Fe⁵⁷, a gyromagnetic ratio of γ/2π = (138.0 ± 0.3) × 10⁴ Hz/T is found in fair agreement with the generally accepted value of (137.7 ± 1.0) × 10⁴ Hz/T.