The magnetic properties of mixed spin-(52,12) anisotropic Heisenberg model in the Oguchi approximation

Abstract

We have used the Oguchi approximation to study the effects of longitudinal crystal (D) and longitudinal external magnetic (h) fields on the mixed spin-(52,12) anisotropic Heisenberg model. The thermal variations of sublattice and total magnetizations are exploited in detail for given values of D, exchange anisotropy parameter (Δ) and coordination numbers z=3,4 and 6 when h=0.0. Thus, the phase diagrams are constructed on the planes of (D/J,kBT/J) and (Δ,kBT/J). In this case, it is found that the model presents either first- or second-order phase transitions as well as tricritical points. In the presence of magnetic field, the hysteresis loops of the model are also analyzed and it was found that the coercive field and remanent magnetization decrease as the temperature increases and increase as the crystal field or the exchange anisotropy increases.