In-situ XANES and XMCD characterization of Fe50Pt50 magnetic nanoparticles

FIGUEROA, S. J. A.; F. G. REQUEJO; S. J. STEWART; A. HERNANDO; P. DE LA PRESA

Campinas, Brasil

Conferencia; 6th International Conference on Synchrotron Radiation in Materials Science; 2008

FePt nanoparticles (NPs) with strong magnetic anisotropy are currently of great interest due to their potential application in data storage medium and biomedicine [1]. In these systems the non-magnetic Pt stabilizes the magnetism of Fe instead of reducing it. However, the detailed mechanism that improves the magnetic properties is still being investigated [2]. On the other hand, special attention is currently being focused in investigating the mechanism involved in the transformation from disordered face-centered cubic structure to an ordered face-centered tetragonal one with high coercitivity and high anisotropy, in addition to the effect of coalescence of particles with annealing. In this work, we focus on the determination of the Fe and Pt magnetic moments using XMCD on FePt particles synthesized by a wet chemical procedure. By dispersive XANES experiments we follow in situ the changes due to annealing on as-prepared FePt NPs. This will allow us to detect possible changes in the electronic state due to the interplay between spin-orbit and polarization between Fe and Pt magnetic moments [2].