Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 6: Magnetic Particles/Clusters II
MA 6.2: Talk
Monday, March 26, 2007, 15:30–15:45, H10
HR-TEM Studies of FePt Nanoparticles by Exit Wave Reconstruction — •Daniela Sudfeld1, Olga Dmitrieva1, Nina Friedenberger1, Günter Dumpich1, Michael Farle1, ChengYu Song2, Christian Kisielowski2, Markus Gruner1, and Peter Entel1 — 1Department of Physics and the Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Lotharstr. 1, 47048 Duisburg — 2National Center for Electron Microscopy, LBNL, One Cyclotron Road, Berkeley CA 94720, USA
To understand the magnetic properties of FePt nanoparticles [1] it is essential to get insights into the lattice structure of isolated clusters. FePt nanocrystals were investigated carrying out a direct reconstruction of the phase and the amplitude of the scattered electron wave from a focal series of HR-TEM images, resulting in a determination of the layer-resolved structure with sub Ångstrom resolution [2]. As an example, the formation of 5-fold twinned structures of 3 to 7 nm sized monodisperse FePt nanocrystals is discussed for fcc particles from colloidal solution and L10 ordered particles prepared by inert gas condensation [3]. In addition, ab initio density functional theory (DFT) calculations of FePt particles with a diameter larger than 2 nm were performed to obtain structural data which were used to model the microscopy data. This work was supported by the DFG (SFB 445) and the EU MRTN-CT-2004-0055667. References: [1] C. Antoniak et al.; Phys. Rev. Lett. 97, No. 11, 117201 (2006). [2] C. Kisielowski et al.; Ultramicr. 89 243 (2001). [3] O. Dmitrieva et al.; J. Phys. D: Appl. Phys. 39 (2006) 4741.