Influence of magnetic field on the critical behavior of La0.7Ca0.2Ba0.1MnO3

The influence of the magnetic field on the nature of the ferromagnetic phase transition as well as the critical behavior of La0.7Ca0.2Ba0.1MnO3 polycrystalline have been studied systematically. Analysis of the Landau- Lifshitz coefficients obtained from Arrott plots showed that b(T) changes from positive to negative values in different magnetic field ranges, indicating that the behavior cannot be described within a single model under the application of a field. The Kouvel-Fisher method, revealed that the critical exponents obtained for La0.7Ca0.2Ba0.1MnO3 strongly depend on the choice of the field range. The b value shifts from the tricritical mean field model to that consistent with short range 3-D Ising model. For the highest field range of 4-5 T, its approaching again the tricritical model. The gamma values are still close to that expected for the mean field model with a slight decrease. These results support evidence of the influence of magnetic field on the coexistence of short-and long-range FM order in La0.7Ca0.2Ba0.1MnO3. The coexistence of short-and long-range FM order is generated from the magnetic inhomogeneity in the sample, which is attributed to the existence of Ca2+ and Ba2+ rich regions. (C) 2014 Elsevier B.V. All rights reserved.