Critical parameters near the ferromagnetic–paramagnetic phase transition in perovskite manganite Pr0.67Sr0.33Mn1−x Al x O3 (0.025 ≤ x ≤ 0.10)

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 \(\Delta S_{\text{M}} \propto H^{n}\), where values n = 0.61–0.62 at Curie temperature (TC) 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.