Length scale for the superconducting Nernst signal above Tc in Nb0.15Si0.85

We present a study of the Nernst effect in amorphous superconducting thin films of Nb0.15Si0.85. The field dependence of the Nernst coefficient above T-c displays two distinct regimes separated by a field scale set by the Ginzburg-Landau correlation length (CL). A single function F (xi), with the CL as its unique argument set either by the zero-field CL (in the low magnetic field limit) or by the magnetic length (in the opposite limit), describes the Nernst coefficient. We conclude that the Nernst signal observed on a wide temperature (30 x T-c) and field (4 x B-c2) range is exclusively generated by short-lived Cooper pairs.