Hyperfine interactions atFe57inFe2+-doped MnCO3

Mössbauer spectroscopy has been used to determine the magnetic state of ${\mathrm{Fe}}^{2+}$ ions that have been substituted for ${\mathrm{Mn}}^{2+}$ in MnC${\mathrm{O}}_3$ for temperatures between 1.8 °K and the Néel temperature (∼ 35 °K). Iron concentrations up to 10 mole% have been examined. Within these ranges, the ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ Mössbauer spectra show marked dependence on both iron content and temperature. The results have been interpreted in terms of the interactions between the magnetic crystal and a single ferrous ion, and support a model proposed recently for this system in which the ${\mathrm{Mn}}^{2+}$ spins are reoriented in the presence of the ferrous ions due to their large single-ion anisotropy in the trigonal crystal field.