Magnetic properties and magnetocaloric effect of diamond-shaped graphene bilayer quantum dots doped with magnetic impurities: A Monte Carlo study

We present an analysis of diamond-shaped graphene bilayer quantum dots doped with magnetic impurities, this study delves into the magnetic properties of the system, employing Monte Carlo simulation. Our numerical results unveil the effect of the magnetic atom concentration x on the magnetizations and susceptibilities of the system, as well as the emergence of various phase diagrams characterized by distinct exchange couplings and anisotropy. We also examine the influence of doping concentration, temperature, and exchange couplings on hysteresis cycles. The magnetocaloric effect of the system is studied in detail. Remarkably, we discovered that strong exchange coupling and an external magnetic field can enhance the magnetocaloric effect of the system, and the relative cooling power can be improved as exchange couplings decrease or the applied magnetic field increases. Our results point to a promising prospect: the incorporation of magnetic ions into graphene bilayer quantum dots (GQDs) offers the potential to finely tune their performance. This intrinsic adaptability not only enhances their current capabilities, but also significantly expands the range of potential applications.