Superconducting fluctuation magnetoconductance in a tungsten carbide film

Abstract

Magnetoconductance (MC) measurements have been performed on a 2140 Å thick tungsten carbide film at temperatures very close to the superconducting transition temperature T_c of the film. The data are dominated by superconducting fluctuations. A novel three-dimensional phenomenological model is proposed to explain the MC data, yielding good fits. The Larkin beta factor, β_Larkin, appeared as a fitting parameter. An expression proposed by Larkin for β_Larkin failed badly for temperatures extremely close to T_c. But at intermediate and high temperatures compared to T_c, Larkin's expression gave very good agreement in fits to the MC data. At temperatures very close to T_c, a crossover from three dimensions to two dimensions was observed in the behaviour of the MC of the film.