Critical and magnetic hysteresis properties of hexagonal core-shell nanowire within a mixed-spin-(5/2,1) Ising-like model: mean-field approach and Monte-Carlo studies

Magnetic properties of mixed-spin-(5/2,1) systems in a hexagonal core-shell nanowire structure based on the Ising-like model with negative core-shell exchange interactions were investigated using the Mean-Field Approximation (MFA), based on the Gibbs-Bogoliubov inequality for free energy, along with Monte-Carlo simulations (MCS) employing the heat bath (Metropolis) algorithm. The findings highlight the significant influence of the spin-5/2 core on the system's magnetic behavior, leading to phenomena such as one or two compensation temperatures, critical end points (CEPs), isolated critical points (ICPs), tricritical points (TCPs) and first- and second-order phase transitions. Furthermore, the effects of various exchange interactions and anisotropy parameters on the thermal phase diagrams were analyzed. The study also explored magnetic hysteresis behavior at low temperatures, revealing multiple transitions involving intermediate spin states and resulting in up to eleven distinct hysteresis loops. These different obtained features can contribute to opening new avenues for research and providing insights into magnetic nanoparticles.