Charge imbalance in superconducting tin films produced by a supercurrent in the presence of a temperature gradient

A pair-quasiparticle potential difference V arising from a quasiparticle charge imbalance has been measured in superconducting tin and tin-indium films along which there exist both a supercurrent I and a temperature gradient ?T. The voltage is proportional to I ?T at a given temperature, and near Tcdiverges approximately as (1 \s- t)\s-1 for given values of I and ?T. Theories by Schmid and Schön and by Clarke and Tinkham are in good agreement with the temperature dependence and magnitude of V/(I ?T), while a theory by Beyer Nielsen et al. predicts the correct magnitude but a temperature dependence of (1 \s- t)\s-1/2.