A Mössbauer study of Pb4Fe3O8Cl,a three-layer magnet

The study of Mössbauer spectra from Pb₄Fe₃O₈Cl allows the observation of crystallographic sites associated with two kinds of magnetic layers present in the structure. Magnetic order appears simultaneously in the two sites below T_N at 602 K. The following features are observed (i) magnetic moments in a plane of easy magnetization perpendicular to the fourfold axis, (ii) antiferromagnetic behavior, as evidenced by the rotation of the magnetic moments under the effect of an external field, (iii) slightly different critical exponents β (0.311 ± 0.003 and 0.295 ± 0.003) for the two magnetic layers.