Crystallographic Domain Structure of an Epitaxial (Pr sub(0.7)Ca sub(0.3))MnO sub(3) Thin Film Grown on a SrTiO sub(3) Single Crystal Substrate

We characterized the structure of the crystallographic domain of a (Pr sub(0.7)Ca sub(0.3))MnO sub(3) (PCMO (x=0.3)) thin film epitaxially grown on a (001)SrTiO sub(3) (STO) single-crystal substrate. We found that the domain structure exhibited an atomically smooth coherent interface with the STO substrate with no misfit dislocations. The crystallographic relationships between the domains and the substrate in their planes were interpreted to be PCMO (x=0.3)[110][001]STO[100][010] and PCMO (x=0.3)[001][1-10]STO[100][010]. The domain structure of PCMO (x=0.3)[110][1-10]STO[100][010] has less possibility of having the larger anisotropic strain energy found in a monoclinically distorted pseudo-cubic perovskite unit cell of PCMO (x=0.3). This epitaxial growth structure is totally different from the previously reported PCMO (x=0.5) epitaxial thin-film structure on STO substrate. Our observations suggested that an x value change strongly influences the structure of epitaxial PCMO thin films.