Volume 79, Number 4, August 2007
Article Number 47006
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 23 July 2007
EPL, 79 (2007) 47006
DOI: 10.1209/0295-5075/79/47006

Threefold onset of vortex loops in superconductors with a magnetic core

M. M. Doria1, 2, A. R. de C. Romaguera1, 2, M. V. Milosevic1, 3 and F. M. Peeters1

1  Departement Fysica Universiteit Antwerpen - Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
2  Instituto de Física, Universidade Federal do Rio de Janeiro - C.P. 68528, 21941-972, Rio de Janeiro RJ, Brazil
3  Department of Physics, University of Bath - Claverton Down, BA2 7AY Bath, UK

received 5 June 2007; accepted in final form 27 June 2007; published August 2007
published online 23 July 2007

A magnetic inclusion inside a superconductor gives rise to a fascinating complex of vortex loops. Our calculations, done in the framework of the Ginzburg-Landau theory, reveal that loops always nucleate in triplets around the magnetic core. In a mesoscopic superconducting sphere, the final superconducting state is characterized by those confined vortex loops and the ones that eventually spring to the surface of the sphere, evolving into vortex pairs piercing through the sample surface.

74.25.Ha - Magnetic properties.
74.25.Op - Mixed state, critical fields, and surface sheaths.
74.78.Na - Mesoscopic and nanoscale systems.

© Europhysics Letters Association 2007