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MA: Fachverband Magnetismus

MA 19: Poster I (Bio- and Molecular Magnetism/ Magnetic Particles and Clusters/ Micro- and Nanostructured Magnetic Materials/ Magnetic Materials/ Multiferroics/ Magnetic Shape Memory Alloys/ Electron Theory of Magntism/ Spincaloric Transport/ Magnetic Coupling and Exchange Bias/ Magnetization Dynamics/ Micromagnetism and Computational Magnetics)

MA 19.21: Poster

Tuesday, March 15, 2011, 10:45–13:00, P2

Magnetic microstructure of nanocrystalline Gadolinium: a small-angle neutron scattering study — •Frank Döbrich^1,4, Helmut Eckerlebe², Melissa Sharp², Joachim Kohlbrecher³, Rainer Birringer⁴, and Andreas Michels¹ — ¹University of Luxembourg, 162A Avenue de la Faïencerie, L-1511 Luxembourg — ²GKSS Forschungszentrum, D-21502 Geesthacht, Germany — ³Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland — ⁴Universität des Saarlandes, D-66041 Saarbrücken, Germany

We report on grain-size dependent magnetic small-angle neutron scattering (SANS) experiments on nanocrystalline Gd, which was synthesized using the low-capturing isotope ¹⁶⁰Gd. The angular variation of the two-dimensional SANS cross-section at different applied magnetic fields is discussed with a special focus on the rather unusual scattering contribution of the clover-leaf-type found for nanocrystalline Gd at intermediate field values. Additionally we have calculated from experimental data the autocorrelation function of the spin misallignment. This approach allows in particular for the extraction of the field-dependent correlation length of static spin misalignment fluctuations induced by microstructural defects. The data analysis suggests that the grain boundaries constitute a major scource of spin disorder in this material, which may be attributed to local atomic site disorder and modified coupling at internal interfaces.