Hamburg 2001 – scientific programme

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TT: Tiefe Temperaturen

TT 4: Josephson Kontakte

TT 4.7: Talk

Monday, March 26, 2001, 16:15–16:30, J

Properties of YBa2Cu3O7 [100]-tilt grain boundary Josephson junctions with high IcRn products on SrTiO3 bicrystals — •U. Poppe, Y. Y. Divin, M. I. Faley, C. L. Jia, P. M. Shadrin, and K. Urban — IFF-IMF, Forschungszentrum Juelich GmbH, Juelich, D-52425, Germany

The electrical and structural properties of YBa2Cu3O7 thin films on vicinal offcut SrTiO3 bicrystals with different grain boundary types were studied. This included junctions with a 2 x 12 degree tilt or twist of the YBa2Cu3O7 c-axis across the grain boundary. In comparison to conventional [001]-tilt grain boundaries bicrystal Josephson junctions [100]-tilt grain boundaries showed high IcRn -products of up to 1.2 meV at 77 K and up to 8 meV at 4.2 K. It will be discussed to what extend this might be attributed to the grain boundary microstructure and the different symmetry relations of the order parameter across the boundary in comparison with conventional [001]-tilt boundaries. Atomic force and transmission electron microscopy were used for microstructural investigations of the grain boundaries.