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MA: Fachverband Magnetismus

MA 13: Poster Ia: Electron Theory (1); Magnetic Imaging (2,3); Thin Films (4-25); MSMA (26-33); Magn. Semiconductors (34-42); Magn. Half Metals and Oxides (43-60)

MA 13.30: Poster

Dienstag, 24. März 2009, 10:15–13:00, P1A

Structure and magnetism of Fe-Pd bulk alloys and nanoparticles from first principles — •Markus Ernst Gruner — Department of Physics and Center for Nanointegration CENIDE, University of Duisburg-Essen, 47048 Duisburg, Germany

In disordered off-stoichiometric Fe₇₀Pd₃₀ and in Fe₃Pt as well as in Ni-Mn-Ga full Heusler alloys the magnetic shape memory (MSM) effect is observed, allowing macroscopic strains of several percent to be achieved in realistic magnetic fields which opens up technological applications as nano- or microscale actuators. The underlying mechanism requires a considerable magnetocrystalline anisotropy in connection with an extremely high mobility of martensitic twin boundaries. In addition, Fe-Pt and Fe-Pd exhibit in their stoichiometric L1₀ phases a magnetocrystalline anisotropy energy being sufficient to entitle them for recording media applications.

This contribution presents ab initio calculations within the framework of density functional theory of the stoichiometric ordered phases of Fe-Pd as well as for disordered systems with MSM relevant composition which are covered within a supercell approach. The investigation covers bulk systems and nanometer-sized clusters which give an account on the influence of surfaces and the possible importance of multiply twinned morphologies.

This work is supported by the Deutsche Forschungsgemeinschaft through SPP 1239 and SFB 445. Part of the computations were carried out on the supercomputers of the John von Neumann Institute for Computing at Forschungszentrum Jülich.