ACTA

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

A. Sazanovich^a, J. Pietosa^a, A. Pashchenko^b, E. Zubov^b, V. Dyakonov^{a, b} and H. Szymczak^a
^aInstitute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland
^bA.A. Galkin Donetsk Physico-Technical Institute, NANU, R. Luxembourg 72, 83114 Donetsk, Ukraine

Received: June 20, 2011 in final form February 15, 2012

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Magnetocaloric effect in (La_0.7Ca_0.3)_{1 - x}Mn_{1 + x}O₃ manganites with x = 0, 0.1, 0.2 has been investigated. It is found a strong influence of nonstoichiometry caused by excessive manganese on the magnetic entropy change. The magnetocaloric effect was evaluated from the isothermal curves of spontaneous magnetization versus the applied magnetic field by using the well-known thermodynamical Maxwell relation. The maximum entropy value, |ΔS_M^max|, near the ferromagnetic-paramagnetic phase transition is shown to increase with the manganese content. The La_0.56Ca_0.24Mn_1.2O₃ manganite exhibits the largest |ΔS_M^max| value equal to 3.09 J kg^-1 K^-1 at 15 kOe near T_C = 267 K. The magnetocaloric effect values obtained allow to propose that the studied manganites are promising materials for future cooling application.

DOI: 10.12693/APhysPolA.122.162
PACS numbers: 75.30.Sg, 61.50.Nw, 65.40.gd