Dynamic phase diagrams and compensation behaviors in molecular-based ferrimagnet AFe~Ⅱ Fe~Ⅲ(C_2O_4)_3 under an oscillating magnetic field

摘要

Within the effective-field theory (EFT), the compensation behaviors in molecular-based ferrimagnet AFe~Ⅱ Fe~Ⅲ(C_2O_4)_3 which is described by a mixed spin-2 (Fe") and spin-5/2 (Fe~Ⅲ) ferrimagnetic Ising model on a honeycomb lattice are studied. The Glauber-type stochastic dynamic is used to describe the time evolution of the system under an oscillating magnetic field. A magnetic field dependence of the compensation temperature and a temperature dependence of compensating magnetic field are calculated and both curves agree qualitatively with experimental data. In particular, a two-compensation-points phenomenon which has been reported in the experimental work is also observed in this compound. Dynamic phase boundaries containing the compensation points are calculated. The dynamic tricritical point and critical end point exist on the phase transition lines. Comparing with previous theoretical results obtained by the mean-field theory (MFT), the effective-field theory results show a reasonable improvement over the MFT results.