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We report an experimental investigation of laser-induced voltages across point-contact junctions of Pt tips and superconductiong Bi compounds. It has been observed that the laser-induced voltages of all 2:2:2:3 granular samples and 2:2:1:2 single-crystal samples are converted with increasing temperature from positive to negative sign, passing through a zero point. The signs for 2:2:1:2 granular samples and n-type Nd 1.85 Ce 0.15 CuO 4+y sample are always positive

The semiconductor-superconductor contact system of Ge/Y-Ba-Cu-O (YBCO)/SrTiO3 has been successfully fabricated by two steps of deposition. The YBCO film in the contact of Ge/YBCO did not lose its superconductivity and its Tc (on set) did not degrade as well. The top layer of Ge was polycrystalline with preferred orientation corresponding to the epitaxial structure of the underlayer of YBCO.

Isothermal V-I characteristics of Bi1.8Pb0.2Sr2Ca2Cu3Oy high temperature superconductors (HTSCs) have been systematically studied. Below the irreversibility temperature Tr(H), two important features were observed: 1) Both positive and negative curvatures can coexist in the same isothermal V-I curve, so it is different from the scaling behavior V ∝ exp(-(J0/J)μ). 2) The activation volume of flux motion is found temperature dependent as (1-T/Tr(H))-2ν with ν about 0.5. This behavior supports the existence of a two-dimensional secondary phase transition below Hc2(T) in this Bi-based HTSCs.

The structure, magnetic, and superconducting properties of the (Tl1-xAlx)2Ba2Ca2Cu3Oy with x = 0.05, 0.1, 0.15, 0.2 were studied. The TcR = 0 depends on whether the sample has a 2223 phase structure or has a 2212 phase structure. The magnetic properties in low field were measured and discussed.