Elastic and inelastic neutron scattering for the study of magnetic thin films and heterostructures

Institut Jean Lamour (UMR CNRS 7198), Université de Lorraine, Vandoeuvre les Nancy, France

Abstract

Neutron-based techniques have proved for decades to be essential tools in the investigation of magnetic materials. The strong experience gathered in neutron centers together with high performance instruments have also largely contributed to the researches on magnetic nanosystems. We will present here a few examples of the use of elastic and inelastic neutron scattering for the study of Dysprosium-based thin films and heterostructures. Elastic neutron scattering in rare earth-based nanosystems provides crucial information both on the crystal structure and the modulated magnetic order. This has especially permitted to connect the drastic change in Curie temperature observed in Dy epitaxial films to modifications of both magnetoelastic and exchange contributions. In superlattices, elastic neutron scattering has been successfully used to analyze the magnetic coupling phenomena, in particular the long range coherent propagation of the Dy helical order. The example of Dy/Er superlattices highlights this fascinating coupling mechanism through either a paramagnetic or magnetic spacer. Inelastic Neutron Scattering is the technique of choice to investigate magnetic excitations over the entire Brillouin Zone. The very low inelastic scattering cross section can however make any investigation of nanosystems very difficult and very few studies have indeed been reported so far on nanosystems. We will show that relevant information could be obtained from high quality single crystalline Dy films and superlattices. These promising results are paving the way to new spin wave explorations in a wider range of magnetic nanosystems.