Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Symposium: Bimetallic Nanosystems: Tuning Physical and Chemical Properties I (Invited Speakers: Harald Brune, Michael Hilgendorff, Konstantin Neyman)

O 60.4: Talk

Thursday, February 28, 2008, 11:00–11:15, MA 005

Irradiation effects in FePt nanoparticles — Michael Müller and •Karsten Albe — Institut f. Materialwissenschaft, TU Darmstadt, Petersenstr. 23, D-64287 Darmstadt

FePt nanoparticles are a promising candidate material for ultra high density data storage because of their huge magnetic anisotropy energy in the chemically ordered L1_o phase (fct). Particles can be prepared in ordered arrays, but are mostly disordered and also occur in multiply twinned configurations. Since thermal annealing leads to a destruction of the patterned arrays, alternative methods are needed to transform the particles into the thermodynamically stable single crystalline ordered phase. In this contribution we use atomic scale computer simulations in order to study the possibility of structural modification and enhanced ordering of L1_o nanoparticles by ion irradiation. Molecular dynamics simulations are used to investigate defect production and sputtering as well as phase transformation processes in twinned and single-crystalline nanoparticles. Lattice-based Kinetic Monte Carlo simulations are employed in order to study the influence of athermal vacancies on the ordering kinetics. We compare the case of He-irradation at low and elevated temperatures while taking into account defect production and sputtering yields as obtained from our MD-simulations.