Dresden 2006 – scientific programme
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MA: Magnetismus
MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)
MA 20.87: Poster
Tuesday, March 28, 2006, 15:15–19:15, P1
Micromagnetic structures of nanocrystalline ferromagnets - comparison of experiment and simulation — •Srinivasa Rao Saranu1, Andreas Grob1, Ulrich Herr1, and Jörg Weissmüller2 — 1Werkstoffe der Elektrotechnik, Universität Ulm, Ulm, Germany — 2Institut für Nanotechnologie, Forschungszentrum Karlsruhe, Karlsruhe, Germany
Bulk nanocrystalline ferromagnetic materials show both hard and soft magnetic behavior depending upon the grain size and exchange length of the magnetic material. Small Angle Neutron Scattering (SANS) experiments show that the local orientation of magnetization averages over many grains at remnant state, whereas some magnetic fluctuations from applied field direction exists even at high external magnetic field. Micromagnetic simulations using the OOMMF code have been done to better understand the experimental results. Irregular random anisotropy nanocrystalline model systems with average grain size of 10 to 100 nm have been generated using a Voronoi construction. The total simulated cell size is 300x300x100 nm. In order to represent bulk nanocrystalline materials, we included anisotropy and exchange energy contributions whereas demagnetizing field energy contributions have been neglected. Magnetic microstructures of the model systems have been investigated at different applied fields and in the remnant state. Correlations of the spatial variations of magnetic moments at different applied magnetic fields were analysed by Fourier transformation. The simulated power spectra agree well with the SANS experimental results. This work has been supported by the Landesstiftung Baden-Württemberg.