normal metal and conventional superconductor. This phenomenon is conventionally explained by Andreev reflection of the tunneling electrons at the interface and the ZBCP height is limited to less than double of the normal conductance at higher bias. However, BSCCO is different from other conventional superconductors because of the d-wave characteristics of the order parameter. There are several ...

A theoretical model for tunneling spectroscopy employing tight-binding band structure, dx2−y2 gap symmetry, group velocity, and tunneling directionality is studied. This is done to investigate if the model can exhibit the same wide range of characteristics observed in tunneling experiments on high-Tc superconductors. A band structure specific to optimallydoped Bi2Sr2CaCu2O8 (BSCCO) is used to c...

We study Andreev states near atomic scale modulations in the pairing potential in both s- and d-wave superconductors with short coherence lengths. For a moderate reduction of the local gap, the states exist only close to the gap edge. If one allows for local sign changes of the order parameter, however, resonances can occur at energies close to the Fermi level. The local density of states (LDOS...

Measurements of the surface impedance, Zs, in Bi 2 Sr 2 Ca 1 Cu 2 O 8+ single crystal with microwave currents owing along the ^ c axis show clear evidence of a step-like nonlinearity. The surface resistance switches between apparently quantized levels for microwave eld strength changes of less than 1 mG. This non-linear response can arise from the presence of intrinsic Josephson junctions along...

Interface instability (or s̀ausaging’) has been a major problem in the oxide powder-in-tube tape-rolling process. The fast Fourier transform of core instabilities are ® rst performed to study the rolled tapes and to obtain quantitative information on the wavelengths and magnitudes of the nonuniform pro® les. The existing experimental observations are also re-examined and summarized. Treating thi...

Numerical simulation of the deformation process during flat rolling of multifilament HTS tapes has been investigated using a commercial FEM program, ELFEN. The numerical models were built up in 2D and 3D using a DruckerPragerKap model for the powder. Three different roll diameters (024 mm, 0 8 5 mm and 0126 mm) have been investigated. It is found that it is possible to perform numerical simulat...

In order to investigate hysteresis losses on Ag-sheathed BSCCO(2223) multifilamentary tapes, we perform hysteresis loop measurements, with the external magnetic field He perpendicular to the tape surface, for different sweep rates of the magnetic field and at different temperatures T. The experimental results show a sweep rate dependence, equivalent to a frequency dependence of the hysteretic l...