Magnetic Ordering in Two Ferromagnetic Sublattices of Two Mixed-Valence Iron(ii)-Iron(iii) Metal Formate Frameworks

Abstract

Temperature dependence of magnetization (M) is calculated for two mixed-valence iron(II) - iron(III) metal formate frameworks (MOFs) with the two ferromagnetic sublattices below T-comp (compensation temperature) at 100 Oe by the molecular field theory. Temperature dependence of magnetization (M-T) is analyzed between T(comp )and T-ord = 39K (ordering temperature) by the power-law formula using the literature data for those compounds. Power-law analysis is also carried out for the field dependence of magnetization (M-H) for 0 < H < 50 Oe interval (T = 2 K) by using the literature data for those MOFs. From both power-law analyses, the temperature-induced (beta) and field-induced (delta) critical exponents for magnetization are deduced for the compounds studied. Calculation and analysis of magnetization for two ferromagnetic sublattice system, indicate that two mixed-valence iron (II)-iron(III) MOFs undergo weakly first order or nearly second order magnetic phase transition.