Critical behavior and room temperature magnetocaloric effect of La-doped Pr0.7Sr0.3MnO3 compounds

In this work, we present the critical and the magnetocaloric properties of Pr(0.7-x)LaxSr(0.3)MnO(3) compounds around room temperature. The samples exhibit a single phase with an orthorhombic structure. However, the lattice parameters increase with an increase in La content (x). The Curie temperature (TC) of the ferromagnetic (FM) paramagnetic (PM) phase transition of compounds increases from 256 K for x = 0-319 K for x = 0.3. We observed a large magnetocaloric effect with high maximum magnetic entropy change (|Delta S-max|) values occurring around room temperature, corresponding to |Delta S-max| = 6.65 and 5.21 J/kgK under a magnetic field change (Delta H) of 50 kOe for x = 0.2 and 0.3, respectively. We also pointed out that the change in |Delta S-max| obeys an exponential function of Delta H (|Delta S-max| similar to Delta H-n), where the value of field exponent (n) is approximately 0.52. Furthermore, the critical behavior around TC for compounds with x = 0.2 and 0.3 has been investigated. The results indicate that these compounds undergo a second-order phase transition with the critical parameters (beta = 0.311, gamma = 1.137, and d = 4.656 at T-C = 298.4 K for x = 0.2; and beta = 0.319, gamma = 1.098, and d = 4.442 at T-C = 318.7 K for x = 0.3) that are quite close to those expected for the 3D-Ising model. This suggests the existence of the short-range magnetic interactions in these compounds.