Influence of Nonstoichiometry on Magnetocaloric Effect in (La_0.7Ca_0.3)_{1 - x}Mn_1+xO₃

Abstract

Magnetocaloric eect in (La0.7Ca0.3)1-xMn1+xO3manganites with x = 0, 0.1, 0.2 has been investigated.It is found a strong inuence of nonstoichiometry caused by excessive manganese on the magnetic entropy change.The magnetocaloric eect was evaluated from the isothermal curves of spontaneous magnetization versus the applied magnetic eld by using the well-known thermodynamical Maxwell relation.The maximum entropy value, |∆S max M |, near the ferromagnetic-paramagnetic phase transition is shown to increase with the manganese content.The La0.56Ca0.24Mn1.2O3manganite exhibits the largest |∆S max M | value equal to 3.09 J kg -1 K -1 at 15 kOe near TC = 267 K.The magnetocaloric eect values obtained allow to propose that the studied manganites are promising materials for future cooling application.