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MA: Fachverband Magnetismus

MA 21: Magnetic Thin Films II

MA 21.11: Vortrag

Mittwoch, 27. Februar 2008, 16:45–17:00, H 1012

Magnetic Excitations in Gd/Y and Dy/Y superlattices investigated with Inelastic Neutron Scattering — •Alexander Grünwald^1,2, Elena Tartakovskaya³, Andrew Wildes², Wolfgang Schmidt⁴, Katharina Theis-Bröhl⁵, Peter Link⁶, Roger Ward⁷, and Andreas Schreyer¹ — ¹GKSS-Research Centre Geesthacht, Germany — ²Institut Laue-Langevin, France — ³Institute for Magnetism, Ukraine — ⁴Jülich Centre for Neutron Science, Germany — ⁵Ruhr-Universität Bochum, Germany — ⁶TU München, Germany — ⁷University of Oxford, UK

Investigations of spin waves in magnetic superlattices are of great interest to understand fundamental properties of magnetism in confined structures. Inelastic neutron scattering is the most versatile technique to study magnetic excitations. The theory predicts discrete energy levels and Brillouin zone folding effects for spin waves propagating along the surface normal in rare earth superlattices. To compare with these calculations, we have investigated a number of Gd/Y and Dy/Y superlattices. Here we present inelastic neutron scattering measurements of low energy excitations. Clear dispersive modes from magnetic excitations and indications on discrete energy levels have been found in both superlattice compounds. The modes have a marked field dependence, particularly for the Gd/Y samples in which a spin wave gap is observed in moderate fields. The observations are in broad agreement with the theory.