[en] The magnetic susceptibility of ternary metal Prussian blue analogues with orthorhombic structure is studied using Ising model. Within the frame work of effective-field theory with correlations, the roles of the mole fraction y, uniaxial magnetic anisotropy, transverse and longitudinal magnetic field are discussed in details. The temperature dependence of the magnetic susceptibility is also investigated. The interesting phenomenon of the inverted magnetic hysteresis loop has been found. The results can help to understand the experimental work of the molecule-based ferri-ferrimagnet.

[en] The magnetic properties of a nanoparticle described by the transverse Ising model with single-ion anisotropis, which consists of a concentric spin-3/2 core and a hexagonal ring spin-5/2 shell coupled with a ferrimamagnetic interlayer coupling, are studied by the effective-field theory with self-spin correlations. Particular emphasis is given to the effects of the both the transverse field and the single-ion anisotropis on the longitudinal and transverse magnetizations, phase diagrams of the nanoparticle. We have found that, for appropriate values of the system parameters, one or two compensation points may be obtained in the present systems.

[en] Based on the effective-field theory with self-spin correlations and the differential operator technique, physical properties of the spin-2 system with biaxial crystal field on the simple cubic, body-centered cubic, as well as faced-centered lattice have been studied. The influences of the external longitudinal magnetic field on the magnetization, internal energy, specific heat, and susceptibility have been discussed in detail. The phenomenon that the magnetization in the ground state shows quantum effects produced by the biaxial transverse crystal field has been found.

[en] The magnetization of a ferrimagnetic mixed-spin nanoparticle for a series of different single-ion anisotropies D1 and D2 with increasing external magnetic field is studied by the use of the effective-field theory with correlations. At low temperature, the magnetization exhibits an obvious step effect for different anisotropies, exchange couplings, and external magnetic field. The results show that the positive single-ion anisotropy D1 (or D2) is a necessary element for the emergence of the accessional magnetization plateaus for the ferrimagnetic mixed-spin nanoparticle. However, for the stronger D2 the magnetization plateaus dissatisfy the 2S+1 criterion in such a ferrimagnetic nanoparticle system.