MAGNETIZATION OF MESOSCOPIC SUPERCONDUCTING DISKS

Solutions of Ginzburg-Landau equations coupled with three-dimensional Maxwell equations reveal an intriguing magnetic response of small supe rconducting particles, qualitatively different from the two-dimensiona l approximation but in agreement with recent experiments. Depending on the radius and thickness, first or second order transitions are found for the normal to superconducting state. For a sufficiently large rad ius of the disk, several transitions in the superconducting phase are obtained which correspond to different angular momentum giant vortex s tates. The incorporation of the finite thickness in the calculation is crucial in order to obtain agreement with the position and the size o f these jumps, and the line shape and magnitude of the magnetization c urves.