STRAIN STABILIZED METAL-INSULATOR-TRANSITION IN EPITAXIAL THIN-FILMS OF METALLIC OXIDE CARUO3

We report the observation of both metallic and semiconducting behavior in epitaxial thin films of the metallic oxide CaRuO3 deposited under identical conditions. X-ray diffraction studies showed that while semi conducting films with enlarged unit cells were obtained on single-crys tal (100) SrTiO3 substrates, metallic films with lattice parameters cl ose to the bulk material grew on (100) LaAlO3 substrates and poor crys talline quality SrTiO3 substrates. It is believed that a strain induce d substitution of the small Ru-4+ cations by the larger Ca2+ cations o ccurs, breaking the conduction pathway within the three-dimensional ne twork of the RuO6 octahedra and leading to a metal-insulator transitio n. This unique phenomenon, which is not observed in bulk material, can be significant in technologically important epitaxial perovskite oxid e heterostructures. (C) 1997 American Institute of Physics.