Magnetocaloric effect of the (Pr,Ca)MnO3 manganite at low temperatures

We have studied the magnetocaloric effect of the Pr1-xCaxMnO3 manganite, with 0.30 <= x <= 0.45, from 2.5 upto 50K. At this temperature range, the (Pr,Ca)MnO3 System present ferro/antiferromagnetic phase mixture which is responsible for the colossal magnetoresistance. Magnetocaloric studies in manganites, up to now, have neglected this magnetic phase mixture, mainly due to the antiferromagnetic phase which is not so well explored in magnetic refrigeration studies as ferromagnetic systems is. In our study, we explain the origin of the negative and positive values of the magnetic entropy change, their temperature dependence as well as the high values. The study of systems with antiferromagnetic phase, as shown in this work, may open an important field in the search of new magnetic materials for magnetic refrigeration. (c) 2004 Elsevier B.V. All rights reserved.