Nucleation of vortices inside open and blind microholes

Abstract

The critical field of a thin superconducting film with a blind circular hole is found theoretically. It is shown that the value of the critical field is sensitive to the bottom thickness, but the orbital momentum, i.e., the number of vortices which nucleate inside the hole, is not sensitive. A simple boundary condition for a steplike thin film is derived and used for comparative numerical analysis of the superconductivity nucleation in a microdisk and near the hole. By increasing the thickness of the bottom of a blind hole one can transform the hole into a disk of the same radius which rests on top of the film. We show that such transformation leads to a jump in the number of vortices which nucleate at the critical magnetic field inside the perimeter of the hole ͑the disk͒. We report also the results of the Bitter decoration experiments of a thin superconducting film with a lattice of open or blind holes. It is found ͑in accordance with the calculation͒ that the bottom thickness has only a weak influence on the number of vortices captured by a hole during the cooling of the sample at a constant perpendicular magnetic field. All the experimental results are explained under the assumption that the vortices nucleated inside a hole rest inside during the cooling process and no additional vortices enter the hole.

Pinning-Induced Formation of Vortex Clusters and Giant Vortices in Mesoscopic Superconducting Disks

“…The only important implication for the present study is that the effect of vortex confinement in single crystal disks is the same as that of confinement in individual thin-film disks, even though in the former case only a small fraction of the total vortex length is subject to the additional interaction with the surface. Moreover, the response is independent of the disk's height, in agreement with theoretical predictions [12].…”

Localization effect in a two-dimensional superconducting network without disorder

“…We have used the Bitter decoration technique to visualize the vortex configuration in the T 3 lattice for f = 1/3 and f = 1/2. As shown recently [11] the decoration contrast can be significantly improved, in the case of superconducting arrays, by using the so-called flux compression method in which a thin superconducting bottom layer converts the network coreless vortices into well-defined Abrikosov vortices. Fig.2 compares the observed vortex patterns for f = 1/3 and f = 1/2.…”

Pinning phenomena in a superconducting film with a square lattice of artificial pinning centers

“…Superconducting films with a lattice of artificial pinning centers (APCs) have been investigated for several years 1,2,3,4,5 . It is found that the vortex lattice is highly ordered at certain matching fields, H n , where the number of flux lines equals an integer multiple n of the number of APCs.…”