Optical response of oxygen deficient La 0.7 Sr 0.3 MnO 3 thin films deposited by pulsed laser deposition

The optical response of 200 nm thick La0.7Sr0.3MnO(3 - delta) films, deposited by pulsed laser deposition on amorphous silica substrates heated at nearly 600 degrees C, under different oxygen pressures (0.1 Pa, 0.5 Pa, 1 Pa, 5 Pa and 10 Pa), is reported. The effects of the oxygen non-stoichiometry are investigated at room temperature dealing with the absorption coefficient and the Tauc's plot method rather than conventional optical conductivity. The absorption curves are evaluated by an algorithm able to realistically describe the behavior of thin films without exploiting numerical extrapolations or simplified theoretical models or ab-initio calculations. Optical features, tunable by the growth oxygen pressure, are discussed based on the known theoretical and experimental scenario. (C) 2013 Elsevier B.V. All rights reserved.