Determination of hyperfine field distributions in amorphous magnets

Abstract

We present an overview of two leading methods of determining probabilitydistributions from Mössbauer spectra, using the model amorphous magnetFe80B20. A comparison is made between the maximum-entropy method, which permitsanalysis using truly arbitrary parameter probability distributions, and aVoigtian-based analysis, which uses a sum of Gaussian components to createparameter distributions of pseudo-arbitrary shape. Our results indicate that, inFe80B20, a Gaussian distribution of magnetic hyperfine fields is a very good approximation,although small deviations from a Gaussian shape are evident. We find that the apparentexistence of correlations between the isomer shift and magnetic hyperfine field parameters,as found using Voigt-based analyses, may be an artefact of imposing a Gaussian shape onthe parameter distributions. We conclude that maximum entropy and Voigtian analysestogether provide a very powerful means of characterizing magnetic materials with Mössbauerspectroscopy.