Continuum versus discrete flux behaviour in large mesoscopic Bi2Sr2CaCu2O8+delta disks

TitleContinuum versus discrete flux behaviour in large mesoscopic Bi2Sr2CaCu2O8+delta disks
Publication TypeJournal Article
Year of Publication2010
AuthorsConnolly MR, Bending SJ, Milosevic MV, Clem JR, Tamegai T
Journal TitlePhysica C-Superconductivity and Its Applications
Date Published12
ISBN Number0921-4534
Accession NumberISI:000286075700384
Keywordsmesoscopic type ii superconductors, multiscale physics, vortex matter

We have used scanning Hall probe and 'local' Hall magnetometry measurements to map flux profiles in superconducting Bi2Sr2CaCu2O8+delta disks whose diameters span the crossover between the bulk and mesoscopic vortex regimes. The behaviour of large disks (>= 20 mu m diameter) is well described by analytic models that assume a continuous distribution of flux in the sample. Small disks (<= 10 mu m diameter), on the other hand, exhibit clear signatures of the underlying discrete vortex structure as well as competition between triangular 'Abrikosov' ordering and the formation of shell structures driven by interactions with circulating edge currents. At low fields we are able to directly observe the characteristic mesoscopic compression of vortex clusters which is linked to oscillations in the diameter of the vortex "dome" in increasing magnetic fields. At higher fields, where single vortex resolution is lost, we are still able to track configurational changes in the vortex patterns, since competing vortex orders impose unmistakable signatures on 'local' magnetisation curves. Our observations are in excellent agreement with molecular-dynamics numerical simulations which lead us to a natural definition of the lengthscale for the crossover between discrete and continuum behaviour in our system. (C) 2009 Elsevier B.V. All rights reserved.

URL<Go to ISI>://000286075700384
Alternate JournalPhysica C