Disorder-induced carrier localization in ultrathin strained SrRuO3 epitaxial films

In this study we explore the influence of disorder on the properties of epitaxial SrRuO3 thin films. Disorder includes interface effects from misfit strain and bulk effects from cation substitutions and interstitial defects. Isostructural perovskites, including LaAlO3, SrTiO3, DyScO3, GdScO3, and BaTiO3, were used as growth platforms to place films under either biaxial tensile or compressive strain. In addition, films on (001)SrTiO3 were codeposited with FeOx, CoO, SrTiO3, and SrFeOx of concentrations up to 10% to compare the disorder distributed throughout the film with the disorder confined to surfaces and interfaces. Pure SrRuO3 films exhibited metallic behavior with low residual resistivity (< 0.1 m Omega cm), and underwent a ferromagnetic transition at a suppressed Curie temperature (T-C) of 145 K. The addition of impurity oxides raised the film's residual resistivity and affected the low-temperature magnetotransport. Interface effects did not seem to play a dominant role in carrier localization, but a few percent of oxide impurities increased the low-temperature resistivity by an order of magnitude. Higher concentrations pushed the resistivity minimum to temperatures comparable to T-C. (C) 2006 American Institute of Physics.