Characterization of magnetic materials by Mössbauer spectroscopy

Since its discovery the Mössbauer effect has been a powerful probe of iron in magnetic materials and, together with neutron scattering and magnetic resonance, complements measurements of magnetic susceptibility and magnetization. The magnetic hyperfine splitting of the spectrum gives a measure of the magnetic moment on the iron atoms, and the line intensities enable the orientation of the magnetic moments to be determined. By applying external magnetic fields the local susceptibility of the iron atoms in paramagnets can be determined, and in magnetically ordered crystals magnetic phase changes may be induced and may be used to measure the magnetic anisotropy. In the early days this was used to determine the magnetic structure of crystalline ferromagnets, ferrimagnets and antiferromagnets. More modern applications include the study of amorphous and disordered crystalline materials (speromagnets, spin glasses, cluster glasses), incommensurate spin structures, fine particle magnets (superparamagnets and superferromagnets), magnetic multilayers, high flux density permanent magnet alloys (e.g. ) and high- superconductors.