RKKY Interactions and Magneto-Caloric Properties of a Nano-Graphene Structure: Monte Carlo study.

The magnetic and magnetocaloric properties of a zigzag triangular nano-graphene with Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange interactions in the mixed 1 and 3/2 spins are studied with the aid of the Monte Carlo investigations. The thermal magnetizations and the magnetic susceptibilities are considered. The phase diagram of the system and the variation of magnetizations with crystal field are established. The magnetic entropy for different external magnetic fields has been also sketched. The dependence of the field on the relative cooling power (RCP) of the system is found; the specific heat displacement of the system is displayed. Also, the adiabatic temperature of the system has been defined. Lastly, the magnetic hysteresis cycle with mixed spins S = 1 and σ = 3/2 for several different parameters is obtained. It can be observed that the values obtained for RCP rise with increasing external magnetic field and reduce with increasing N for constant parameters. The critical temperature values are also affected by the increasing number of non-magnetic layers. In addition, the effect of the RKKY interaction decreases as 1/N2. As a consequence, the system becomes rapidly out of order as the number of non-magnetic layers N is increased. [ABSTRACT FROM AUTHOR]