title: Size-dependent spin structures in iron nanoparticles.
abstract: Using photoemission electron microscopy, we study the magnetization orientation in single 5-25 nm iron particles coupled to a ferromagnetic cobalt support. We find a noncollinear alignment between the particle and substrate magnetization above a particle size of approximately 6 nm and a parallel alignment for smaller sizes. Numerical calculations reveal a transition from an exchange-dominated to an anisotropy-dominated regime on increasing the particle height: the smaller particles are in a single-domain collinear state while larger particles exhibit a spin-spiral magnetic structure determined by the magnetic anisotropy energy.
authors.affiliation: Paul Scherrer Institut, Villigen PSI, CH-5232 Switzerland. arantxa.fraile-rodriguez@psi.ch
authors.forename: A
authors.initials: A
authors.lastname: Fraile Rodríguez
authors.forename: A
authors.initials: A
authors.lastname: Kleibert
authors.forename: J
authors.initials: J
authors.lastname: Bansmann
authors.forename: A
authors.initials: A
authors.lastname: Voitkans
authors.forename: L J
authors.initials: LJ
authors.lastname: Heyderman
authors.forename: F
authors.initials: F
authors.lastname: Nolting