Magnetocaloric properties in La1−xCaxMnO3 thin films: Monte Carlo simulations

• Thermal behavior of entropy, susceptibility and isothermal entropy change is studied.
• ΔS and ΔT present a transition at the critical temperature depending on the stoichiometry.
• Semi-classical Heisenberg Hamiltonian allows simulation of magnetocaloric effect in LCMO.
• External magnetic field produces changes in ΔS and ΔT observed in the shifting of TC.

The magnetocaloric effect (MCE) of La1−xCaxMnO3 was analyzed when varying the stoichiometry (x=0.2, 0.33, 0.4 and 0.5) and the external applied magnetic field. Simulations were carried out using the Monte Carlo method having a configuration ascribed by the set Sz of all-site spin projections, under the Metropolis algorithm. La1−xCaxMnO3 is characterized for three types of magnetic ions corresponding to Mn4+ (S=3/2), which are bonded to Ca2+, and Mn3+(eg) and Mn3+(eg′, S=2), which are both bonded to La3+. Different interactions must be considered depending on the type of interacting ions. The entropy change ΔS in an isothermal process as well as the temperature change ΔT in an adiabatic process was determined with this model. Both ΔS and ΔT show stoichiometry-dependent maximums near the paramagnetic–ferromagnetic transition temperature (TC), confirming the order–disorder change at this temperature. The strong dependence in La1−xCaxMnO3 of the MCE on the stoichiometry and the external magnetic field makes this phenomenon important for different technological applications, particularly in refrigeration.