Abstract
In order to further understand the newly developed homo-biepitaxial junctions and the dependence of the critical current density with the tilt grain boundary angles, we spent lots of time on reproducing a good 450 bi-epitaxial structure with pure in-plane rotations in each part. However, we found that it was rather difficult to achieve the bi-epitaxial rotation angles with the original homo-biepitaxial structures [YBCO(high-T)/YBCO(low-T)/YSZ and YBCO(high-T)/YSZ]. Besides, an overall survey of in-plane epitaxial relationships between YBCO and YSZ was done. We found that the in-plane rotations strongly depend on the deposition temperatures and substrate surface properties. Due to this reason, we modified the bi-epitaxial structure becoming YBCO(8300C)/ YBCO(6600C)/ YSZ (in-plane rotation 450) and YBCO(8300C)/ YBCO(6600C)/ YBCO(8300C)/ YSZ (in-plane rotation 00). The grain boundary Josephson junction made of this modified structure exhibits the RSJ behavior and the Jc is ~ 103 A / cm2 at 4.2 K. However, the Ic-H measurements show that there is no obvious relation between faceting distribution and the tilt grain boundary angles.