Charge-ordering contribution to the magnetic entropy change of [formula omitted] manganites

Abstract

In the present work, we analyze the influence of the charge-ordering on the magnetic entropy change of Pr1-xCaxMnO3 manganites (0.20<x<0.95). The samples with x<0.30 and x>0.90 present the usual ferromagnetic and antiferromagnetic behavior, peaking at the Curie and Néel temperature, respectively. In contrast, for the samples with charge-ordering (0.30<x<0.90), a much smaller positive peak on the magnetic entropy change was observed around the charge-ordering temperature TCO. This effect is associated to a negative contribution from the spin ordering ΔSspin, which is superimposed to a positive contribution due the charge-ordering ΔSCO. We could also appraise ΔSCOmax as a function of Ca content (0.30<x<0.90), under 4T of magnetic field change. ΔSCOmax vanishes for the limits x∼0.30 and ∼0.90, and presents a deep minimum around x∼0.50, with two maxima at x∼0.35 and 0.65.