JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, vol.540, 2021 (SCI-Expanded)
Magnetic, thermal and ferroelectric properties of MOFs (metal organic frameworks), in particular, the compounds CH3NH2NH2M(HCOO)(3) (MHyM) with M = Fe and Mn, are studied close to phase transitions. For the magnetic properties, the molecular field theory at low temperatures and the power-law formula within the framework of an Ising pseudospin-phonon coupled model close to TC are performed by using the observed magnetization data for MHyFe and MHyMn from the literature. For the thermal properties, particularly, the heat capacity CP, Ising compressible model with the power-law formula is introduced to analyze the experimental data by considering the two anomalies in CP at the critical temperatures (TC1 and TC2) for MHyFe and MHyMn. Within these two anomalies, the ferroelectric properties of MHyMn are also studied by analyzing the observed data for the spontaneous polarization PS using the power-law formula.