Paraconductivity of three-dimensional amorphous superconductors-evidence for a short-wavelength cutoff in the fluctuation spectrum

Measurements of the temperature dependence and magnetic-field dependence of the paraconductivity of a three-dimensional amorphous superconductor are presented. The data are analyzed in terms of several current theories and are found to give good agreement for low fields and temperatures near $T_c$. Strong pair-breaking effects due to thermal phonons are believed to account for the observed absence of anomalous Maki-Thompson contributions to the paraconductivity. The paraconductivity falls well below predicted theoretical values in the high-temperature and high-field limits. This is attributed to the reduced role of high-wave-vector contributions to the paraconductivity. It is shown that the introduction of a short-wavelength cutoff in the theoretical fluctuation spectrum provides a phenomenological account of the discrepancy between theory and experiment.