Dresden 2006 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 16: Growth Processes and Surface Properties
DY 16.5: Vortrag
Montag, 27. März 2006, 17:15–17:30, H\"UL 186
Simulation of binary alloy cluster growth: Segregation, exchange processes, magnetic interactions and magnetic field effects — •Mario Einax1, Stefan Heinrichs1, Philipp Maass2, and Wolfgang Dieterich1 — 1Fachbereich Physik, Universität Konstanz, D-78457 Konstanz — 2Institut für Physik, Technische Universität Ilmenau, D-98684 Ilmenau
We present detailed kinetic Monte Carlo (KMC) simulations of growing nanoclusters on a weakly interacting substrate within a fcc-type binary alloy model. This model is designed to describe recent molecular beam epitaxy experiments on CoPt3 nanoclusters that develop perpendicular magnetic anisotropy (PMA) [1]. As a consequence of Pt surface segregation (driven by exchange processes) and cluster shape we find a growth-induced structural anisotropy, located near the cluster surface, which is compatible with experimentally observed magnetic properties [2]. Analytic approaches are discussed to clarify the competition between the incoming flux and surface equilibration processes leading to kinetically limited surface segregation.
In a second step our model is generalized to include an external magnetic field in the growth direction, which is found to induce bulk structural anisotropy favorable for PMA. Moreover, magnetic interactions are shown to have a significant influence on the bulk transition temperature for the onset of L12-ordering [3].
[1] M. Albrecht et al., Europhys. Lett. 56, 884 (2001)
[2] S. Heinrichs et al., cond-mat/0510196
[3] M. Einax et al., to be published