Transmission electron microscopy of La0.7Ca0.3MnO3 thin films

La0.7Ca0.3MnO3 (LCMO) films grown on (0 0 1) surfaces of various (pseudo-) cubic substrates, MgO, SrTiO3, LaSrGaO4 and YAlO3, were studied by means of transmission electron microscopy. In all cases, the (0 0 1) plane of LCMO perovskite primitive cell is parallel to the substrate surface. The film on SrTiO3 showed the single-variant structure with many twin boundaries while the films on other substrates had the three-variant structure where three [0 1 0] axes of the orthorhombic unit cell are perpendicular to each other. The LCMO cell on SrTiO3 was expanded by about 1% in the film plane and shrank by about 1% out of the plane. Many planar defects and intergrown grains were observed in the film on MgO. They originated at the substrate surface.