Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 5: Invited Talks Pätzold / Gruner
MA 5.2: Hauptvortrag
Montag, 26. März 2007, 14:30–15:00, H10
Structural and magnetic properties of transition metal nanoparticles from first principles — •Markus Ernst Gruner, Georg Rollmann, Alfred Hucht, and Peter Entel — Dept. of Physics, University of Duisburg-Essen, Campus 47048 Duisburg
Until recently, the simulation of transition metal particles in the nanometer range was only feasible with semi-empirical approaches and classical molecular dynamics simulations. However, the close interrelation of electronic and structural properties often leaves no alternative to a fully quantum mechanical treatment. The evolution of modern supercomputer technology nowadays allows for the simulation of nanometer-sized objects from first principles in the framework of the density functional theory (DFT). A technologically relevant example is the search for ultra-high density magnetic recording media where the decrease of the magnetic grain size competes with the inset of superparamagnetism. Here, FePt nanoparticles are discussed as a promising solution due to their large magnetocrystalline anisotropy in the ordered L10 phase. However, in experiment also other, less favorable, structures are observed. Therefore, a systematic ab initio investigation of the morphologies of FePt particles concerning their energetics and magnetism at sizes relevant for future application appears highly desirable. Within this contribution, we report on DFT calculations of Fe and FePt clusters of up to 561 atoms including full geometric optimization. The calculations were carried out using the Vienna Ab initio Simulation Package (VASP) on up to 2048 processors on the IBM BlueGene/L installation at Forschungszentrum Jülich.