STRUCTURAL, MICROSTRUCTURAL AND ELECTRICAL PROPERTIES OF La0.67Ca0.33MnO3 FILMS DEPOSITED VIA PULSED LASER DEPOSITION

Abstract

La_0.67Ca_0.33MnO₃ films were prepared by pulsed laser deposition on single crystal MgO (100) glass substrates with different deposition times and post-annealed at 800 °C and 900 °C to study their influence on the physical properties. All samples showed orthorhombic crystal structure as observed from the X-ray diffraction analysis. LCMO films exhibited double phases (La_0.67Ca_0.33MnO₃ and La_0.15Ca_0.85MnO₃) when post-annealed at 800 °C attributed to the insufficient energy of LCMO particles in forming the single crystalline phase at lower temperature. As the samples were post-annealed at 900 °C, the particles obtained the optimise energy to re-crystalline and forms pure La_0.67Ca_0.33MnO₃ phase. The formation of layer-by-layer structure accompany with some agglomerations of the grains have been observed in 800 °C of post-annealed samples. Meanwhile, irregular shape particles were obtained for samples that were post-annealed at 900 °C and some cauliflower-like structure can be seen at some part of the film. From electrical measurement, the highest value of T_MI (metal-insulator transition) has been observed in LC-M10-8 sample (152 k). It is found that the lower the thickness of the film, the higher the T_MI value due to less energy of electrons that pass through the grain boundaries thus resulting a lower resistivity.