Inelastic-tunneling model for the linear conductance background in the high-Tcsuperconductors

The linear conductance background observed in tunneling into the high-${\mathit{T}}_{\mathit{c}}$ superconductors has often been interpreted as a density-of-states effect. Here we argue that it may be due instead to strong inelastic electron tunneling from a broad, flat continuum of states. We provide a specific model for such a continuum of states in the high-${\mathit{T}}_{\mathit{c}}$ superconductors based upon a form for the spin-fluctuation spectral weight which fits NMR data, and compare the predictions of this model with experiment.