La(Ca)MnO3 manganitlerin yapısal ve manyetodirenci üzerine nadir toprak elementleri katkılamanın etkisi

We have investigated the influence of Europium (Eu) doping on structuraland magneto-electrical properties of La0.7Ca0.3MnO3 compounds. In order toanalyze the physical mechanism of a spin disorder system and study their relativeevolutions, two samples of nominal compositions (La0.7?xEux)Ca0.3MnO3(x = 0.0 and 0.1) have been elaborated and characterized. In addition to structuralchanges seen by this kind of doping, the magnetoresistance (MR) and resistivityare increased while the metal-insulator transition temperature is decreased.Comparing the experimental data with the theoretical models shows that in themetal-ferromagnetic region, the electrical behaviour of both samples is quite welldescribed by a theory based on Kondo-like spin dependent scattering, electronelectronscattering, electron-phonon and electron-magnon scatterings. For thehigh temperature paramagnetic insulating regime, the adiabatic small polaronhopping model is found to fit well the experimental curves.