A new metallic, ordered perovskite thin film La6.4Sr1.6Cu8O22: pulsed laser deposition and microstructural characterization

Abstract

Pulsed laser deposition has been used to prepare thin films of a new perovskite, La_6.4Sri_1.6Cu₈O₂₂ with ordered oxygen vacancies. Energy dispersive scattering analysis confirms the stoichiometric deposition of the cations from the ceramic target, La_6.4Sri_1.6Cu₈O₂₀ Electron diffraction and high-resolution electron microscopic (HREM) studies show that the cell parameters are a=b= 2a_p√2 and c=a_p= 3.86 Å, but that the structure of the film differs from the target, bulk material, and suggests that the film is more oxygenated, according to the composition La_6.4Sri_1.6Cu₈O₂₂. The HREM images can be simulated from a model in which one-half of the oxygen vacancies in the bulk structure are filled. The film is well crystallized, [110] oriented with respect to the LaAlO₃ substrate, and exhibits good metallic conductivity.