Vortex contribution to the excess noise in superconducting transition

We report voltage noise studies on thin tin films in the superconducting transition region to understand the mechanism of the excess noises observed in the transition. Temperature and I-V characteristics studies suggest evidence of a Kosterlitz-Thouless transition for the thin Sn films studied. A correlation of the onset of rapid increases of noise with the power law in I-V points to the dominant vortex contribution to the excess noises, consistent with the characteristic \sqrt{V} dependence of the spectral power of the noise.