Critical parameters near the ferromagnetic-paramagnetic phase transition in perovskite manganite Pr_0.67Sr_0.33Mn_1-xAl_xO₃ (0.025 ≤ x ≤ 0.10)

We have determined the values of critical exponents of three mixed manganite Pr_0.67Sr_0.33Mn_1-xAl_xO₃ (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 ΔS_M∝ Hⁿ, 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. (orig.)