Transport properties of Bi2Sr2Ca2Cu3O10+δ Bicrystal Grain Boundary Josephson Junctions and SQUIDs

Josephson junctions and SQUIDs on 36.8° SrTiO 3 bicrystal substrates were prepared from epitaxial Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ thin films with critical temperatures around 95K. The current-voltage characteristics are well described by the resistively and capacitively shunted junction model. I c R n products of 50μV at 77K and 0.7mV at 4.2K have been reached. The I c (B) dependence is symmetric to B = 0 with an I c suppression of 90% in the first minimum. Nevertheless it turns out, that the junctions are inhomogeneous on a μm scale. SQUID modulations observed at 78K indicate a flux-voltage transfer function of 2.7μV/Φ 0 at this temperature.