Characteristics of c axis and ab axis tunneling in s-wave superconductors

The peculiarities in tunneling characteristics have been studied in the light of the controversy between s-wave and d-wave character of high Tc superconductivity. It is shown that anisotropic s-wave gap has the same voltage power law conductance and two peak structure in the density of states as d-wave superconductors. The asymmetric tunneling conductance and zero bias conductance for the c-axis tunneling is shown to occur because of finite band splitting coming from the interlayer hopping parameter. The characteristics features which have been so far studied in this area have been attributed to d-wave superconductors. Here it was found that these features are not unique to the d-wave theory and can also be realised in the context of the s-wave theory. (author). 10 refs., 4 figs