Thermodynamic Properties of Random Transverse Field Mixed Spin System in the Presence of Single-Ion Anisotropy

We study the thermodynamic properties of random transverse field mixed spin system in the presence of single-ion anisotropy on a square lattice. By making use of the effective field theory and a cutting approximation, the detailed phase diagrams are described and some interesting results are found under trimodal random transverse fielddistribution. A small single-ion anisotropy can magnify magnetic orderingregion at low temperatures and existence of a large transverse field can assist the occurrence of reentrant phenomena. With increasing disorder,second-order phase transitions are shown to change into first-order phasetransitions. The trajectory of the tricritical point in the phase space as a function of disorder is presented. These indicate a strong correlation withthe corresponding to trimodal transverse field distribution.