Effect of Eu doping on structural and magneto-electrical properties of La0.7Ca0.3MnO3 manganites

We have investigated the influence of europium (Eu) doping on structural and magneto-electrical properties of La0.7Ca0.3MnO3 compounds. In order to analyze the physical mechanism of a spin disorder system and study their relative evolutions, two samples of nominal compositions (La0.7-xEux)Ca0.3MnO3 (x = 0.0 and 0.1) have been elaborated and characterized. In addition to structural changes seen by this kind of doping, the magnetoresistance (MR) and resistivity are increased while the metal-insulator transition temperature is decreased. Comparing the experimental data with the theoretical models shows that in the metal-ferromagnetic region, the electrical behaviour of both samples is quite well described by a theory based on Kondo-like spin dependent scattering, electron-electron scattering, electron-phonon and electron-magnon scatterings. For the high temperature paramagnetic insulating regime, the adiabatic small polaron hopping model is found to fit well the experimental curves. (c) 2011 Elsevier B.V. All rights reserved.