Polycrystalline Perovskite Manganese Oxide Films Obtained by Laser Ablation

摘要

With regards to application to sensors, the La_(0.7)Sr_(0.3)MnO_3 polycrystalline films are well-suited systems, owing to its relatively high Curie temperature (about 360 K) and the saturating behaviour of the magnetoresistance due to the grain-boundary transport contribution. Therefore, we have grown La_(0.7)Sr_(0.3)MnO_3 polycrystalline thin films by pulsed laser deposition (PLD) with a KrF laser at two different O_2 pressures (0.3 and 0.05 mbar). The targets were produced by ceramic and sol-gel method and the substrates used were Si with an amorphous SiO_2 buffer layer and polycrystalline Al_2O_3. The films were heated during the deposition at about 500℃and were crystalline without need of further annealing. Microstructure study was performed by X-ray diffraction and scanning electron microscopy. Magnetotransport measurements have been performed at room temperature, obtaining MR of about 4 % at 1 T and at room temperature. Thus, it seems fairly adequate for obtaining magnetic sensors based in manganite oxides.