title: Glassy vortex dynamics induced by a random array of magnetic particles above a superconductor.
abstract: The magnetic relaxation of a Nb film covered with a random array of permalloy particles has been studied using various procedures. When the sample undergoes a field-cooled process, the magnetic relaxation becomes logarithmic in time. The relaxation rate is nearly temperature independent at low temperature and characteristic glassy dynamics-aging and memory effects-are observed. These results are interpreted as the consequence of pinning by the statistical variation of the number of nanoparticles within the area of a vortex core.
authors.affiliation: Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Young
authors.initials: Y
authors.lastname: Sun
authors.forename: M B
authors.initials: MB
authors.lastname: Salamon
authors.forename: K
authors.initials: K
authors.lastname: Garnier
authors.forename: R S
authors.initials: RS
authors.lastname: Averback