Phase diagrams and magnetisations of mixed spin nanoparticles with transverse field and crystal field

Using the finite cluster approximation, we investigate the phase transitions of two mixed spin 2D-nanoparticles. The effects of the crystal field and the transverse field parameters on phase diagrams and magnetisations have received the most attention. In a certain range of surface shell coupling, the model exhibits a tricritical behavior when only a longitudinal crystal field is present. The reentrance behavior may occur when the core and shell...