title: Vortex fusion and giant vortex states in confined superconducting condensates.
abstract: In a direct scanning tunneling spectroscopy experiment we address the problem of the quantum vortex phases in strongly confined superconductors. The strong confinement regime is achieved in in situ grown ultrathin single nanocrystals of Pb by tuning their lateral size to a few coherence lengths. Upon an external magnetic field, the scanning tunneling spectroscopy revealed novel ultradense arrangements of single Abrikosov vortices characterized by an intervortex distance up to 3 times shorter than the bulk critical one. At yet stronger confinement we discovered the giant vortex phase; the spatial evolution of the excitation tunneling spectra in the cores of these unusual quantum objects was explored. We anticipate the giant vortex phase to be a common feature of other confined quantum condensates such as superfluids, Bose-Einstein condensates of cold atoms, etc.
authors.affiliation: Institut des Nanosciences de Paris, Université Pierre et Marie Curie-Paris 6 and CNRS-UMR 7588, 4 place Jussieu, 75252 Paris, France.
authors.forename: T
authors.initials: T
authors.lastname: Cren
authors.forename: L
authors.initials: L
authors.lastname: Serrier-Garcia
authors.forename: F
authors.initials: F
authors.lastname: Debontridder
authors.forename: D
authors.initials: D
authors.lastname: Roditchev