title: Magnetization reversal of individual Co nanoislands.
abstract: We investigate the magnetization reversal of individual Co islands on Cu(111) in the size range of N=700 to 18,000 atoms by spin-polarized scanning tunneling microscopy at 8 K. The switching field H(sw) changes with island size in a nonmonotonic manner: it increases with island size and reaches a maximum value of 2.4 T at N=5500 atoms, and it decreases for larger islands. We extract the energy barrier for magnetization reversal as a function of island size. The maximum H(sw) corresponds to an energy barrier of 1 eV. Our results elucidate a crossover of the magnetization reversal from an exchange-spring behavior to domain wall formation with increasing size at around 7500 atoms.
authors.affiliation: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle/Saale, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Ouazi
authors.forename: S
authors.initials: S
authors.lastname: Wedekind
authors.forename: G
authors.initials: G
authors.lastname: Rodary
authors.forename: H
authors.initials: H
authors.lastname: Oka
authors.forename: D
authors.initials: D
authors.lastname: Sander
authors.forename: J
authors.initials: J
authors.lastname: Kirschner