Nontrivial Shapes of the Mössbauer Spectra of Magnetic Nanoparticles with Different Forms of Magnetic Anisotropy

Abstract—The continual and quantum-mechanical models of magnetic dynamics are considered for a system of ferromagnetic nanoparticles with different forms of magnetic anisotropy alongside with the corresponding theory for describing the Mössbauer spectra of such materials. The calculations of spectra in these models demonstrate various forms of the magnetic hyperfine structure upon the evolution of the absorption spectra of nanoparticles from a well-resolved magnetic hyperfine structure (sextet of lines for ⁵⁷Fe nuclei) at low temperatures to a single line or a five-stage pedestal at high temperatures. These models substantially broaden the methodological basis for the diagnostics of magnetic nanomaterials by the method of Mössbauer spectroscopy.