Nanostructured Fe and FePd studied by Mössbauer spectroscopy

Mössbauer spectra of nanostructured Fe and FePd (∼29% Pd) have been measured at temperatures between 4.2 K and room temperature and at 4.2 K in applied magnetic fields of 7.0 T and 14.3 T. While some agreement is obtained with earlier measurements on nanostructured materials also prepared by gas condensation, differences in the relative magnitudes of the hyperfine magnetic fields of the two major components and their temperature dependences are observed. The applied field spectra reveal differences in the magnetic behaviour of the narrow line component linked with the ferromagnetic nanocrystalline grains and the broad line component linked with the interfacial regions. Differences in the hyperfine parameters from sample to sample may be due in part to relaxation effects in the interfacial boundary regions leading to structural changes.