Interpretation of the Mossbauer spectra of speromagnetic materials

A reinterpretation by Pankhurst and Pollard (1990-1992) of the Mossbauer spectra of amorphous ferric compounds in terms of an antiferromagnetic model requires uniaxial anisotropy K1 approximately 2*106 J m-3. This is two orders of magnitude greater than usual for ferric oxides, and comparable with the anisotropy of rare earth permanent magnet materials. In the absence of any physical justification for such huge uniaxial anisotropy, the original interpretation in terms of a speromagnetic model stands.