Superconducting and anomalous electron transport properties and electronicstructure of BaNbO3-x and Ba2Nb5Ox films - art. no. 174512

We have investigated the superconducting (T-c,J(c),H-c2), electron transpor t, structural [x-ray diffraction (XRD), Rutherford backscattering spectrome try (RBS)], and surface [x-ray photoelectron spectroscopy (XPS), ultraviole t photoelectron spectroscopy (UPS)] properties of BaNbO3-x and Ba2Nb5Ox epi taxial and oriented thin films grown on different substrates (Al2O3, NdGaO3 , SrTiO3, and YSZ). Superconducting films with T-c = 14 K and unusually hig h H-c2(0) = 28 T have been prepared on Al2O3 substrates. At the same time, films on NdGaO3 exhibit behavior similar to granular superconductors, while strong pure metal electron transport behavior of the films on SrTiO3 was o bserved. XPS and RES investigations show that the composition of these film s is almost the same, while UPS study evidenced the Fermi edge position cor responding to semimetallic behavior of the films for all substrates.