NMR study of La3+ substituted hexagonal ferrites with magnetoplumbite structure

Domain 57Fe NMR spectra of La3+ substituted hexagonal ferrites Pb1−xLaxFe12O19 and Ba1−xLaxFe12O19 have been measured at 4.2 K using the spin echo technique. Besides the five main lines, the satellite lines caused by the substitution were observed. The assignment of the satellite lines to the Fe3+ sublattices was made using the dependence of the NMR spectrum on the external magnetic field. The experimental results are explained assuming the existence of Fe2+ ions in the 2a sublattice.