Bandwidth control effects in electron doped manganite La(0.7-x)Y(x)Ce(0.3)Mno(3) thin films

摘要

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 (T-p) and the ferromagnetic Curie temperature (T-c) are found to be decreasing significantly with increasing yttrium concentration, i.e. decreasing < r(A)>. The resistivity (rho) at T-p increases by one order of magnitude when the yttrium concentration is increased from x = 0 to 0.25, while magnetization decreases with decreasing < r(A)>. Magnetoresistance as measured under field of 1 T is significant near T-c. Structural analysis reveals the films are having single phase and c-axis lattice parameter decreasing linearly as < r(A)> 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. (c) 2006 Elsevier Ltd. All rights reserved.