Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 23: Magnetic Thin Films II
MA 23.14: Vortrag
Mittwoch, 25. März 2009, 18:00–18:15, HSZ 04
Dispersion relation separation revealed by inelastic neutron scattering on Dy/Y and Gd/Y superlattices — •Alexander Grünwald1, Elena Tartakovskaya2, Andrew Wildes3, Wolfgang Schmidt4, Gregor Nowak5, Katharina Theis-Bröhl6, Roger Ward7, Peter Link8, Astrid Schneidewind9, and Andreas Schreyer1 — 1GKSS-Research Centre, Geesthacht, Germany — 2Institute for Magnetism, Kiev, Ukraine — 3Institut Laue-Langevin, Grenoble, France — 4Jülich Centre for Neutron Science, Germany — 5Ruhr-Universität Bochum, Germany — 6University of Applied Sciences, Bremerhaven, Germany — 7University of Oxford, United Kingdom — 8Forschungsneutronenquelle Heinz Maier Leibnitz, Garching, Germany — 9Technische Universität Dresden, Germany
Special features of the magnetic dispersion relations in long-range exchange-coupled rare earth superlattices have been revealed with inelastic neutron scattering and can be explained by our theory. In details we have investigated magnetic low energy excitations propagating normal to the interfaces in Dy/Y and Gd/Y superlattices. The data, obtained by cold three-axis-spectroscopy, strongly suggest a separation of the 'continuous' bulk dispersions into discrete energy levels and Brillouin zone folding effects, due to the periodic sample structures and the finite number of magnetic atomic planes in each bilayer. The observed inelastic intensities are broad in energy though, but match with similar results on a (thick) Dy film. A considerably opening of the spin wave gap at the Brillouin zone center has been found as a function of an increasing applied magnetic field on the Gd/Y superlattices.