Point-contact characteristics obtained with single-phase Y-Ba-Cu-O superconductors

Superconductor-superconductor point contacts have been successfully made using Y-Ba-Cu-O samples. The samples prepared were defined single-phase material: orthorhombic ${\mathrm{Y}}_{0.35}$ ${\mathrm{Ba}}_{0.65}$ ${\mathrm{CuO}}_{3\mathrm{-}\mathrm{n}}$ with a volume susceptibility close to 100% and a critical temperature of 90 K (midpoint). I-V and (dV/dI)-V characteristics of the point contacts clearly show superconducting critical currents and gap features when operating at 4.2 K.