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.

Vortex structure of thin mesoscopic disks in the presence of an inhomogeneous magnetic field

“…In order to investigate such structures in our case we use the method proposed by Schweigert et al 7 and Palacios 8,9 and extended it to determine the stability of the different multi-vortex configurations as proposed in Ref. 20 . Following Refs.…”

“…Theoretical studies have predicted that in mesoscopic disks surrounded by an insulating media three kinds of superconducting states can exist -giant vortex (a circular symmetric state with a fixed value of angular momentum), multi-vortex state (a collection of single vortices which can be obtained as a linear combination of giant vortices with different angular momentum), and ring-shaped vortex states 20,21 with larger energy than giant and multi-vortex states. The ring-shaped two-dimensional vortex states have a cylindrically symmetric magnetic field profile and they are different from the ring-vortices which are e.g.…”

“…In order to investigate these different vortex structures we use the method proposed by Schweigert et al 7 and Palacios 8,9 , with its semi-analytical extensions of Ref. 20 to determine the stability of the different multi-vortex configurations. In particular, the analysis of Ref.…”

“…In particular, the analysis of Ref. 20 showed that in a superconducting disk the ring-shaped vortices are unstable in the presence of a homogeneous magnetic field..…”

The role of the boundary conditions on the critical properties of superconducting rings under the action of a tranversal magnetic field

“…The obtained relations can be used to consider the influence of the radial confinement on the so called enhanced superconductivity [11]. Additionally, these results can be extended in order to discuss the influence of boundary conditions at the outer edge.…”