Vortex structure of thin mesoscopic disks with enhanced surface superconductivity

Abstract

The vortex state in a thin mesoscopic disk surrounded by a medium which enhances surface superconductivity is investigated theoretically in the framework of the phenomenological Ginzburg-Landau theory. We calculated the dependences of both the ground and metastable states on an external magnetic field perpendicular to the disk plane for different values of the order parameter angular moment, i.e., the vorticity. The magnetic field-temperature phase diagram is obtained and the regions of existence of the multivortex state and the giant vortex state are found. We analyzed the phase transitions between these states. Our results are also applicable for the analysis of the vortex state in extreme type-II mesoscopic disks.