Critical exponents and magnetic entropy change across the continuous magnetic transition in (La, Pr)-Ba manganites

The critical behavior and magnetocaloric effect (MCE) in the perovskite system La0.7−xPrxBa0.3MnO3 (x = 0.05, and 0.15) have been carefully investigated via dc-magnetization measurement. With the increase in Pr-doping, the universality class shifts from the predicted 3d-Heisenberg model characterized by a short-range coupling [β = 0.371 ± 0.008, γ = 1.351 ± 0.002 and δ = 4.634 ± 0.002, for x = 0.05] to an unknown one [β = 0.385 ± 0.004, γ = 1.324 ± 0.001 and δ = 4.435 ± 0.006, for x = 0. 15]. The critical exponents, however, obey the scaling behavior for both samples. Likewise, this series of compounds displays rescaled magnetic entropy data that plead in favor of a non-universal MCE behavior. Moreover, the field dependence of the magnetic entropy change (ΔSM) gives rise to critical exponents (β and γ) which are not consistent with that estimated through the critical …