Superconductive fluctuations in the density of states and tunneling resistance in high-Tcsuperconductors

The effect of superconductive fluctuations on the density of states and tunneling resistance is revisited in the case of dirty superconductors and derived for clean samples with and without pair-breaking sources. For clean superconductors new features appear in the density of states. In particular, with respect to the commonly known dirty case, the fluctuation effects manifest themselves on a new scale of energy with a different power-law behavior as function of T-${\mathit{T}}_{\mathit{c}}$. The relevance of these results for high-${\mathit{T}}_{\mathit{c}}$ superconductors is analyzed.