Length scale for the superconducting Nernst signal aboveTcinNb0.15Si0.85

Abstract

We present a study of the Nernst effect in amorphous superconducting thin films of ${\mathrm{Nb}}_{0.15}{\mathrm{Si}}_{0.85}$. 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 $F(\ensuremath{\xi})$, 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 $(30\ifmmode\times\else\texttimes\fi{}{T}_{c})$ and field $(4\ifmmode\times\else\texttimes\fi{}{B}_{c2})$ range is exclusively generated by short-lived Cooper pairs.