Thermodynamic properties and magnetocaloric effect of a graphdiyne bilayer with RKKY interaction

•A ferromagnetic mixed spin Ising model was used to describe the graphdiyne bilayer with JRKKY interaction.•Thermodynamic properties and magnetocaloric effect were presented by Monte Carlo simulation.•Magnetic entropy change caused by exchange coupling, nonmagnetic layer and external magnetic field were discussed.•The relative cooling power RCP under the external field change was obtained. Based on the Monte Carlo method, a ferromagnetic mixed spin-3/2 and spin-5/2 Ising model is extended to research the thermodynamic and magnetocaloric properties of the graphdiyne bilayer under the presence of the external magnetic field. The results of the finite-size effect show that the thickness of the nonmagnetic layers and the total number of the atoms have the significant influence on the studied quantities including magnetization, susceptibility, internal energy, specific heat, magnetic entropy, and magnetic entropy change. In addition, the maximum of the magnetic entropy change -ΔSm can be improved by increasing the exchange interaction between atoms b in the bottom magnetic surface Jb/Ja and adding the nonmagnetic layers L. We also obtain the relative cooling power RCP under the change of the external field Δh/Ja.