The effect of the fluence on the properties of La-Ca-Mn-O thin films prepared by pulsed laser deposition

Thin films of La0.6Ca0.4MnO3-delta were deposited on SrTiO3(100) by PRCLA (Pulsed Reactive Crossed-Beam Laser Ablation). The dependence of the structural and transport properties of the films on the laser fluence and different target to substrate distances during the growth are studied. Both parameters have a direct influence on the films thickness and velocity of the ions arriving at the substrate, which influence the film properties directly. The surface roughness of the La0.6Ca0.4MnO3-delta thin films is depending mainly on the laser fluence and less on the target-substrate distance. Lower laser fluences and therefore lower growth rates yield film with lower roughness, i.e. in the range of 0.2 nm. The electronic transport measurements show a decrease of the transition temperature from metal to semiconductor with an increase of the target to substrate distance. This is related to an increase of the films thickness and therefore decrease of the strain in the films due to the lattice mismatch with the substrate. The magnetoresi stance values are also strongly affected by the tensile strain, i.e. they increase for higher strained films. (c) 2007 Elsevier B.V. All rights reserved.