AVS 53rd International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI-TuM

Invited Paper MI-TuM3
Orbital Magnetism of Fe and Pt in Monodisperse FePt Nanoparticles

Tuesday, November 14, 2006, 8:40 am, Room 2006

Session: Magnetic Nanostructures, Nanoparticles and Interfaces
Presenter: M. Farle, Universitaet Duisburg-Essen, Germany
Authors: M. Farle, Universitaet Duisburg-Essen, Germany
C. Antoniak, Universitaet Duisburg-Essen, Germany
K. Fauth, MPI Stuttgart, Germany
M. Spasova, Universitaet Duisburg-Essen, Germany
F. Wilhelm, ESRF, France
A. Rogalev, ESRF, France
Correspondent: Click to Email
X-ray absorption (XAS)and x-ray magnetic dichroic spectra (XMCD) were measured at both the Fe and Pt L@sub3,2@ edges on wet-chemically synthesized monodisperse Fe@sub50@Pt@sub50@ particles with a mean diameter of 6.3 nm before and after complete removal of the organic ligands and the oxide shell covering the particles by soft hydrogen plasma resulting in a pure metallic state. After thermal treatment of the metallic particles, the coercive field increased by a factor of 6, the orbital magnetic moment at the Fe site increased by 330% and decreased at the Pt site by 30%, while the effective spin moments did not change. A decrease of the frequency of oscillations in the extended x-ray absorption fine structure (EXAFS) at the Pt L@sub3,2@ edges provides evidence for crystallographic changes towards the L1@sub0@ phase. These results are discussed in context to recent results revealing a layerwise structural relaxation of the surface layers in FePt nanoparticles.