Transport properties of high-temperature superconductor + semiconductor composites with different carrier concentration

Results are presented of an experimental study of the temperature dependence of the electrical resistivity ρ(T), critical current density J _c(T), and current-voltage characteristics of polycrystalline composites based on the high-temperature superconductor Y_3/4Lu_1/4Ba₂Cu₃O₇ and copper oxide with different lithium doping levels. The experimental temperature dependence of the critical current of composites with varying volume content of the semiconductor ingredient and varying charge carrier concentration are found to be in qualitative agreement with theory which takes account of Andreev reflection of the carriers at the S-Sm and Sm-S surfaces of the S-Sm-S Josephson junction (where S is the superconductor and Sm is the semiconductor). Fiz. Tverd. Tela (St. Petersburg) 39, 829–834 (May 1997) Deceased