Sample size dependence of excess resistance near critical field in mesoscopic superconducting Al disk

We report the size dependence of superconducting transition in mesoscopic Al disks with 1.0, 0.7, and 0.4? m in diameter performed by resistance measurements under magnetic field. All the samples show excess resistance peaks near Hc2, which are 3 ~ 6 times larger than normal state resistance Rn, whereas there are no resistance peaks at H = 0. We find that the resistance peak rapidly increases and becomes the largest at the magnetic field just below the transition of vorticity L : 0 ? 1 with no relation to the sample size. The resistance peak, which shows the presence of large energy dissipation, would be caused by characteristic vortex dynamics confined in the small geometries.