OBSERVATION OF NONUNIFORM CURRENT TRANSPORT IN EPITAXIAL YBa2Cu3O7– x FILM NEAR THE SUPERCONDUCTING TRANSITION TEMPERATURE
نویسندگان
چکیده
We have studied the local transport properties in an epitaxial YBa2Cu3O7 x (YBCO) film on LaAlO3 (LAO) using variable temperature scanning laser microscope (VTSLM) near the superconducting transition. A map of the superconducting transition temperature ðT c Þ is generated from a series of VTSLM images. The map of T c indicates there are inhomogeneities in the film large enough to create nonuniform current flow near the superconducting transition. The evaluated T c varies between 90.3 and 91.0 K in the film. Even though such change in T c is not large enough to be detected by other localized compositional and structural characterization techniques, this along with an area of lower T c and/or higher resistance affects current flow near the superconducting transition temperature as shown in VTSLM images. This inhomogeneity may be caused by slight variations of the stoichiometry and/or oxidation of the YBCO film. 2004 Elsevier B.V. All rights reserved. PACS: 74.62.)c; 74.72.Bk; 74.76.Bz
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