Abstract
We have determined the values of critical exponents of three mixed manganite Pr0.67Sr0.33Mn1-xAlxO3 (x = 0.025, 0.05 and 0.1) from the magnetization data versus temperature and magnetic field M(H, T), to learn about their magnetic and magnetocaloric properties. Experimental results revealed that these samples exhibits a continuous (second-order) paramagnetic (PM) to ferromagnetic (FM) phase transition. The critical properties near ferromagnetic-paramagnetic phase transition temperature have been analyzed from data of static magnetization measurements for the samples, using various techniques such as modified Arrott plot (MAP), Kouvel-Fisher (KF) method and critical isotherm (CI) analysis. The critical exponents values estimated from the isothermal magnetization measurements are found to be consistent and comparable to those values predicted short-range 3D Heisenberg model. The field dependence of the magnetic entropy change is also analyzed, which shows the power law dependence, namely Delta S-M proportional to H-n, where values n = 0.61-0.62 at Curie temperature (T-C) are quite far from than the mean-field predictions (n = 2/ 3). The deviation from the mean-field behavior is due to the presence of local inhomogeneities in the vicinity of a transition temperatures.