Intrinsic high electrical conductivity of stoichiometric SrNbO3 epitaxial thin films

SrVO3 and SrNbO3 are perovskite-type transition-metal oxides with the same d(1) electronic configuration. Although SrNbO3 (4d(1)) has a larger d orbital than SrVO3 (3d(1)), the reported electrical resistivity of SrNbO3 is much higher than that of SrVO3, probably owing to nonstoichiometry. In this paper, we grew epitaxial, high-conductivity stoichiometric SrNbO3 using pulsed laser deposition. The growth temperature strongly affected the Sr/Nb ratio and the oxygen content of the films, and we obtained stoichiometric SrNbO3 at a very narrow temperature window around 630 degrees C. The stoichiometric SrNbO3 epitaxial thin films grew coherently on KTaO3 (001) substrates with high crystallinity. The room-temperature resistivity of the stoichiometric film was 2.82 x 10(-5) Omega cm, one order of magnitude lower than the lowest reported value of SrNbO3 and comparable with that of SrVO3. We observed a T-square dependence of resistivity below T* = 180K and non-Drude behavior in near-infrared absorption spectroscopy, attributable to the Fermi-liquid nature caused by electron correlation. Analysis of the T-square coefficient A of resistivity experimentally revealed that the 4d orbital of Nb that is larger than the 3d ones certainly contributes to the high electrical conduction of SrNbO3.