Metastability and paramagnetism in superconducting mesoscopic disks

A projected order parameter is used to calculate not only local minima of t he Ginzburg-Landau energy functional but also saddle points or energy barri ers responsible for the metastabilities observed in superconducting mesosco pic disks [A. K. Geim et al., Nature (London) 396, 144 (1998)]. We calculat e the local minima magnetization and find the energetic instability points between vortex configurations with different vorticity. We also find that, for any vorticity, the supercurrent can reverse its flow direction on decre asing the magnetic field before one vortex can escape.