Temperature and field dependences of the magnetization and the magnetic susceptibility in perovskite structures (FMDMn and AceMn) -2

Ferromagnetic properties of the perovskite structures, namely, [NH<inf>2</inf>–CH+–NH<inf>2</inf>] [Mn(HCOO)<inf>3</inf>] (FMDMn) and [CH<inf>3</inf>C(NH<inf>2</inf>)<inf>2</inf>] [Mn(HCOO)<inf>3</inf>] (AceMn), are studied close to magnetic phase transitions. Magnetization M(T) is calculated by the extended mean field model, and M(H) is analyzed for FMDMn near T<inf>c</inf> = 8 K. For AceMn, this analysis is performed using M / H(c¢<inf>ac</inf>) and M(H) near T<inf>c</inf> = 9 K. The observed data from the literature are used for the power-law analysis. The critical exponents b, d, and g for M(T), M/H, and M(H), respectively, are determined, which are compared with the expected values from the mean field theory, Ising and Heisenberg models. We find that the Landau mean-field model satisfactorily describes the magnetic behavior of M(T) values for the perovskite FMDMn. Our g and d values are not in agreement with those expected ones. It is indicated that both compounds (FMDMn and AceMn) exhibit weak first-order (or nearly second-order) behavior; in particular, a tricritical magnetic transition is suggested for FMDMn. © H. Yurtseven, A. Kurt, and M. Kurt, 2025.