Bandwidth control effects in electron doped manganite La0.7−xYxCe0.3MnO3 thin films

We report the effect of average A-site cation radius on the structural, magnetic and electrical properties of electron doped manganite La0.7Ce0.3MnO3 thin films. A site cation radius 〈rA〉 is varied systematically by partially replacing La+3 ions by smaller Y+3 ions in the parent compound. The carrier doping, i.e. the fraction of tetravalent Ce atoms at the A-site was kept at 30%. A series of La0.7−xYxCe0.3MnO3 (x=0, 0.05, 0.1, 0.15 and 0.25) thin films were prepared under identical conditions by using pulsed laser deposition technique. Metal–insulator transition temperature (Tp) and the ferromagnetic Curie temperature (Tc) are found to be decreasing significantly with increasing yttrium concentration, i.e. decreasing 〈rA〉. The resistivity (ρ) at Tp increases by one order of magnitude when the yttrium concentration is increased from x=0 to 0.25, while magnetization decreases with decreasing 〈rA〉. Magnetoresistance as measured under field of 1 T is significant near Tc. Structural analysis reveals the films are having single phase and c-axis lattice parameter decreasing linearly as 〈rA〉 decreases. There is no marked difference in surface morphology of samples with different yttrium concentration. From EDX the Y:Ce:Mn ratio were consistent within 5% of the nominal composition.