Mössbauer spectroscopy of magnetic nanoparticles: From universal qualitative treatment to realistic models of magnetic dynamics for particles of different magnetic nature and nanomaterial diagnostics

A unified phenomenological model of the magnetic dynamic of an ensemble of nanoparticles of different magnetic nature is developed. The model can be applied to the numerical analysis of Mössbauer spectra as functions of the temperature and external field. The model allows us to describe nonstandard features of the temperature evolution of the spectrum shape, particularly the macroscopic quantum effects often observed in the spectra of ⁵⁷Fe nuclei in antiferromagnetic nanoparticles.