Grain-boundary junctions in high Tc superconducting oxides

Superconducting Josephson weak links can be produced at the grain-boundary in high transition temperature(Tc) superconducting oxides. Artificial grain-boundaries, such as the bicrystal grain-boundary formed by the epitaxial growth of a high Tc thin film on a bicrystal substrate, is a wavy line and faceted. The d-wave pairing symmetry of the superconducting order parameter and the faceting of the grain-boundary have important effects on the characteristics of the grain-boundary. We review the relevent research of recent years in this field.