Magnetism in some layer molecular magnets as revealed by Mossbauer spectroscopy

Fe-57 Mossbauer spectroscopy was used to explore magnetic properties of two 2D molecular ferrimagnets. In NPn(4)[(FeFeIII)-Fe-II(ox)(3)] (Pn= n-C5H11, ox=(C2O4)(2-)), the previously reported negative magnetization is shown he re by external field studies to be due to a cross-over between Fe-III and F e (II) magnetizations. The form and parameters of the magnetic Hamiltonian describing the temperature dependence of both the Fe-III hf-field and net m agnetizations has been determined. In NBu4[(MnFeIII)-Fe-II(ox)(3)] (Bu = n- C4H9) soft XY-magnet the low temperature relaxation spectra are interpreted in terms of slowly varying classical magnetization-evolution at low temper ature.