Dr. Andrew Wildes (Institut Laue-Langevin, Grenoble, France)

Neutronenclub N-337/338, Building 04.8

"Inelastic neutron scattering from rare-earth superlattices and thin films"

In principle, inelastic neutron scattering is the ideal technique for measuring magnetic lattice dynamics on the atomic scale.  The technique is flux limited, however, meaning that usually samples must be relatively large to have statistically significant count rates.  Thus, the use of the technique to measure materials with inherently small masses, such as thin films, multilayers, and superlattices, has not been seriously pursued.

Experiments are feasible, however, and we have successfully applied the techniques to Dy/Y and Gd/Y superlattices and Dy thin films.  The data unambiguously show spin waves.  They have been quantitatively modelled with theory developed specifically for the measurements showing evidence for discrete energy modes and, in the case of the helical Dy/Y superlattices, the influence of Dzyaloshinsky-Moryia anisotropy.

The presentation will summarize the measurements and the conclusions regarding the physics of these materials, with emphasis on the experimental techniques that were used detailing their advantages and limitations for measurements of similar samples.  There will also be a short presentation on the possibilities of using neutron reflectometers for inelastic scattering.

Kontakt

Alexander Weber

Telefon: +49 89 158860-726

Fax:  +49 89 158860-799

E-Mail: al.weber@fz-juelich.de