Study of magnetocaloric effect and magnetic properties of the nano-graphene bilayer with RKKY interactions of a mixed spins S=3/2 and σ=3: a Monte Carlo simulation

In this study, we have used Monte Carlo simulations that explain the magnetic properties and magnetocaloric effect of a nano-graphene bilayer separated by non-magnetic layers with mixed spin 3/2 and 3 with RKKY (Ruderman-Kittel-KasuyaYosida) exchange coupling. We present and discuss ground state phase diagrams that have been found. Also, the reduced critical temperature is obtained for several values of the number of non-magnetic layers (NM). The system can exhibit a phase transition from the ferromagnetic to the paramagnetic phase at a reduced critical temperature. The effect of the parameter NM, the reduced exchange interactions (S-S), (sigma -sigma), and the reduced crystal field on the total magnetizations and the established hysteresis loops are investigated. Specific heat, specific heat change, thermal magnetization dM/dT, and magnetic entropy changes as a function of the temperature for various reduced external magnetic fields were investigated in detail. Finally, we report the influence of different values of reduced magnetic field h/J(s sigma) on the relative cooling power.