The influence of substrate orientation and annealing condition on the properties of LaMnO3 thin films grown by polymer-assisted deposition

The epitaxial films of LaMnO3 were fabricated via a simple polymer-assisted deposition method. The effects of substrate orientation and annealing condition on the structure and properties of LaMnO3 films have been investigated. It is found by X-ray diffraction and Raman spectroscopy that increase in the oxygen content results in a decrease in unit cell volume along with a reduction in Jahn-Teller distortion. Besides, with increase in annealing temperature, the resistivity of the film decreases and the insulator-metal transition temperature TIM shifts to higher temperature. The maximum of the resistivity is highly substrate-orientation dependent in the ascending order of (1 0 0) < (1 1 0) < (1 1 1). Furthermore, the TIM of LaMnO3 film increases with the substrate orientation changing from (1 1 1) to (1 0 0). It is shown that magnetic order correlates well with an insulator to metal behavior. All results reveal that the lattice distortion of MnO6 octahedron can be tuned by different annealing condition and the substrate orientation, which can be effective methods to adjust the structure, electrical and magnetic properties of LaMnO3 films.