title: Symmetric and asymmetric vortex-antivortex molecules in a fourfold superconducting geometry.
abstract: In submicron superconducting squares in a homogeneous magnetic field, Ginzburg-Landau theory may admit solutions of the vortex-antivortex type, conforming to the symmetry of the sample [L. F. Chibotaru, Nature (London) 408, 833 (2000)10.1038/35048521]. Here we show that these fascinating, but never experimentally observed states, can be enforced by artificial fourfold pinning, with their diagnostic features enhanced by orders of magnitude. The second-order nucleation of vortex-antivortex molecules can be driven by either temperature or an applied magnetic field, with stable asymmetric vortex-antivortex equilibria found on its path.
authors.affiliation: Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Geurts
authors.forename: M V
authors.initials: MV
authors.lastname: Milosević
authors.forename: F M
authors.initials: FM
authors.lastname: Peeters