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

Josephson junctions and SQUIDs on 36.8° SrTiO3 bicrystal substrates were prepared from epitaxial Bi2Sr2Ca2Cu3O10+δ thin films with critical temperatures around 95K. The current-voltage characteristics are well described by the resistively and capacitively shunted junction model. IcRn products of 50µV at 77K and 0.7mV at 4.2K have been reached. The Ic(B) dependence is symmetric to B = 0 with an Ic 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/Φ0 at this temperature