The mixed spin-3/2 and spin-2 Blume-Capel model by renormalization group approach

Purpose The authors investigate the magnetic properties of a mixed spin-3/2 and spin-2 Blume-Capel model on square and cubic lattices with two different single-ion anisotropies. Design/methodology/approach To study the critical behavior of a mixed spin-3/2 and spin-2 system, the authors have used a real space renormalization group approximation and specifically the Migdal-Kadanoff technique. The authors give the phase diagrams for two different cases: (1) on the (Delta/|J|, 1/|J|) plane with Delta(A) = Delta(B) = Delta, and (2) on the (Delta(A)/|J|, 1/|J|) and (Delta(B)/|J|, 1/|J|) planes for selected values of Delta(B)/|J| and Delta(A)/|J|, respectively. Findings The phase diagrams obtained show that the system exhibits both second- and first-order phase transitions as well as tricritical points for some values of the anisotropies. Moreover, using the variation of the free energy and its derivative at low temperatures, the authors have seen the appearance of first-order transitions at very low temperatures. Originality/value Few investigations of mixed spin-3/2 and spin-2 systems with crystal field have been realized. For this reason, the authors use the renormalization group approach to complete the work done on these systems. In absence of an exact solution, this contributes to the synthesis of the approximation results on mixed spins models.

Automated summary

The authors investigated the magnetic properties of a mixed spin-3/2 and spin-2 Blume-Capel model using a real space renormalization group approximation. The phase diagrams obtained show different phase transition behaviors, including second- and first-order transitions as well as tricritical points, for varying values of anisotropies. This study contributes to the synthesis of approximation results on mixed spins models in the absence of an exact solution.