2026/08/03 by Basit Iqbal, Kingshuk Sarkar
Physics and Astronomy · #cond-mat.stat-mech
28 pages, 14 Figures
arxiv created 2026/08/03 · arxiv updated 2026/08/04
We report a Monte Carlo study of the magnetocaloric effect (MCE) in two-dimensional ferromagnetic Ising models on square, honeycomb, and triangular lattices with monolayer and bilayer configurations. Using Binder cumulant analysis, we determine the critical temperature (Tc) of each structure and find that Tc increases with coordination number, from the honeycomb (r=3) to the triangular (r=6) lattice. In contrast, the magnetic entropy change (-ΔSM) decreases with coordination number, reaching its maximum for the honeycomb lattice. After normalization by their peak values and appropriate temperature scaling, both -ΔSM and the field exponent n collapse onto universal master curves for different magnetic fields and across all six lattice structures at a fixed low field. This demonstrates universal MCE scaling independent of coordination number and layer count. Critical scaling analysis further supports the observed universality and power-law behavior. Unlike -ΔSM, the adiabatic temperature change (ΔTad) increases with coordination number, whereas the magnetic Grüneisen parameter (ΓM) follows the same trend as -ΔSM. Although the peak value of -ΔSM decreases with coordination number, the relative cooling power and cooling capacity remain nearly unchanged due to compensating broadening of the -ΔSM curves. The field dependence of -ΔSM, relative cooling power, and cooling capacity follows power laws up to ∼2.6 T (assuming J≈1 meV). Hysteresis analysis shows that lattices with lower coordination numbers exhibit a faster reduction in loop width with increasing temperature. These results establish the universal scaling behavior of the magnetocaloric effect in two-dimensional monolayer and bilayer magnetic lattices and provide guidelines for designing magnetic refrigerants.