Calculation of Magnetization and Magnetic Susceptibility Close to Magnetic Phase Transitions in (CH3)(2)(NH2FeNiII)-Ni-III(HCOO)(6) and (CH3)(2)(NH2FeCuII)-Cu-III(HCOO)(6)

Abstract

We study the temperature and magnetic field dependence of the magnetization (M) and the inverse susceptibility (chi(-1)) in the metal-organic frameworks, in particular, for (CH3)(2)(NH2FeNiII)-Ni-III(HCOO)(6) (DMFeNi) and (CH3)(2)(NH2FeCuII)-Cu-III(HCOO)(6) (DMFeCu) close to their magnetic phase transitions. The Landau phenomenological model is employed to analyze the experimental data for the M(T, H) from the literature and to calculate chi(-1)(T, H) of DMFeNi and DMFeCu. Our results indicate that the thermodynamic model studied explains adequately the observed behavior of M(T, H) for DMFeNi and DMFeCu, which exhibit a weakly first-order (or nearly second order) magnetic phase transition.