Rare earth effect on the critical behavior of La0.75Ln0.05Sr0.2MnO3 manganites

Abstract

In this work, we have investigated the effect of rare earth substitution in La0.75Ln0.05Sr0.2MnO3 (Ln˭La, Sm, Eu, Gd, Dy and Ho) manganites on the critical behavior near the magnetic phase transition temperature. Different techniques were used to determine the values of the critical exponents β, γ and δ as well as transition temperature TC. The reliability of the critical exponents values was confirmed by both Widom relation and scaling hypothesis. In the case of Ln˭La, Sm, Eu, Gd and Ho, the magnetic interactions were described by 3D-Ising model. However, the substitution by Dy ions changes the universality class from 3D-Ising to tricritical mean field, which can be ascribed to the intrinsic contribution of Dy3+ ions.