Critical behavior investigated through magnetocaloric effect in PrSrMnO and Pr(Sr,Ca)MnO manganites

In this work we investigate the critical behavior of two manganite compounds, Pr0.5Sr0.5MnO3 (PSMO) and Pr0.5Sr0.41Ca0.09MnO3 (PSCMO). These are complex magnetic systems, which undergo a paramagnetic to ferromagnetic phase transition on cooling, followed by a first order magnetic transition to a charge ordered antiferromagnetic states at lower temperatures. Magnetization measurements and magnetocaloric calculations were performed in order to determine their critical behavior. As a main result we show that the scaling of the entropy change - Delta SM with magnetization M, instead of the usual scaling with magnetic field H, is a powerful tool to study the critical behavior through magnetocaloric analysis. We use this property, in conjunction with Modified Arrot Plot technique, to determine the basic critical exponents beta and gamma for each sample. The exponents values indicate that the samples are near to universality class models based in nearest neighbor interactions. Besides intrinsic differences between the Ca-doped and the undoped sample, we confirm the applicability of the magnetocaloric analysis in order to determine critical behavior in complex magnetic systems.