Influence of different post-annealing temperatures on physical properties of La0.72Ca0.28MnO3:Ag0.2 thin films by pulsed laser deposition technique

Abstract

La0.72Ca0.28MnO3:Ag0.2/LaAlO3 (100) thin films, prepared by pulsed laser deposition, were post-annealed at different temperatures in air. X-ray diffraction technique were used to analysize the orientation and lattice parameter, atomic force microscope (AFM) and scanning electronic microscope (SEM) were employed to characterize the surface morphology of the thin films. Resistance vs. temperature (R-T) behaviors of the thin films were tested with standard four-probe technique. The surface morphology results show that the grain size increases and crystalline quality of the films are improved with increased annealing temperature up to 1200 °C, while the amount of grains also increases; R-T results illustrate that both the temperature coefficient of resistance (TCR) and metal-insulator transition temperature (TMI) of the films, increase with annealing temperature. In particular, TCR of thin film (post-annealing at 1200 °C) reaches 28.8%·K−1, which makes such films be promisingly applicated in thermal detectors near the room temperature.