Electrical and magnetoresistivity studies in chemical solution deposited La(1-x)CaxMnO3 thin films

High quality magnetoresistive La(1-x)CaxMnO3 thin films have been prepared by the chemical solution deposition technique. A solution of propionate pre cursors of lanthanum, calcium, and manganese in propionic acid was used for this purpose. Films of varying compositions (x varying from 0.1 to 0.4) we re spin coated on to LaAlO3(100) and SrTiO3(100) substrates at room tempera ture and pyrolyzed in the temperature range 600-850 degreesC. For fixed com positions, annealing at higher temperatures shifts the insulator-metal tran sition temperature (TI-M) to higher values accompanied by a reduction in th e resistivity values. The TI-M variation for different x values was found t o be less pronounced in the compositions x = 0.2, 0.3, and 0.4. Typical TI- M values of 283 K and 290 K were obtained for La0.7Ca0.3MnO3 coated on LaAl O3 and SrTiO3 substrates, respectively, when annealed at 850 degreesC. The substrate effect was found to be more pronounced for the x value 0.1 which showed two peaks (one at 271 K and another at 122 K) in the rho -T curve. T he roles of substrate mismatch, composition variation, and annealing temper atures are discussed. (C) 2001 American Institute of Physics.