Effect of sodium deficiency on the critical behavior near the paramagnetic to ferromagnetic phase transition temperature in La0.8Na0.2-x□xMnO3 oxides

The critical behavior associated with the magnetic phase transition has been investigated by in La0.8Na0.2 (x)square xMnO3 (0.00 <= x <= 0.15) (square is the sodium deficiency). The critical exponents are estimated by various techniques such as the modified Arrott plot, Kouvel-Fisher plot and critical isotherm technique. Compared to standard models, the critical exponent values determined in our work are close to those expected by the tricritical model (beta = 0.25, gamma = 1, and delta = 5) for x = 0.00 and 0.05 samples and by mean field theory (beta = 0.5, gamma = 1, and delta = 3) for x = 0.10 and 0.15 samples. We conclude that the Na deficiency rate affect the critical exponents. (C) 2017 Elsevier B.V. All rights reserved.