The morphological evolution in ${\mathrm{La}}_{0.5}{\mathrm{Ca}}_{0.5}\mathrm{Mn}{\mathrm{O}}_3∕\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3\left(100\right)$ ultrathin films has been revealed by atomic force microscopy. It was found that ordered linear defects, which are in 1–2 unit cells high and oriented along the cubic [110] and [100] directions, first appear on the smooth surface of films with a thickness of $10\mathrm{nm}$. As the epitaxial growth proceeds, these lines on surface develop into a crosshatch pattern for films with a thickness of $25\mathrm{nm}$. Using the results of transmission electron microscopy and electrical measurements, we discuss the interplay between the surface pattern formation, the internal dislocation structure, and the variations in the electrical properties.

• Received 28 May 2007

DOI:https://doi.org/10.1103/PhysRevB.77.115330