| AVS 57th International Symposium & Exhibition | |
| Actinides and Rare Earths Topical Conference | Tuesday Sessions |
| Session AC+MI-TuM |
| Session: | Actinide and Rare Earth Magnetic Interfaces & Nanostructures |
| Presenter: | G.J. Mankey, University of Alabama |
| Authors: | J. Yu, University of Alabama H. Sato, University of Alabama P.R. LeClair, University of Alabama G.J. Mankey, University of Alabama J.L. Robertson, Oak Ridge National Laboratory R.S. Fishman, Oak Ridge National Laboratory |
| Correspondent: | Click to Email |
Inelastic neutron scattering is the world's most powerful tool to study the magnetic excitations of solids. We aim to study spin wave dispersion relations in multilayer structures and how they are affected by the indirect RKKY exchange interaction through nonmagnetic spacers. Dy was chosen as the magnetic film since it has a huge magnetic moment of 10.2 Bohr magnetons and the neutron scattering cross section is directly proportional to the atomic moment. For elastic scattering, a film with thickness of order 100 nm is sufficient, but inelastic neutron scattering has a considerably lower cross-section requiring much more material for measurement. To enable such a study, many samples with tightly-controlled thickness and crystallinity must be fabricated. The neutron experiments can then be performed by stacking 8-10 samples, each with 50-100 superlattice repeats. The number of repeats for each sample is limited by the accumulation of defect structures over the growth front. Using a home-built sputtering system, we have achieved the ability to make suitable samples. The system has computer-controlled magnetron sputtering guns and a sample tranfer system which enables continuous sample rotation of a 2" diameter wafer at 900ºC during sputtering in an ultra-pure environment. Maintaining a good vacuum is essential since both Y and Dy are highly reactive and form stable oxides with only a minute amount of oxygen in the sputtering environment. In addition, the dispersion relations of the spin wave modes are highly sensitive to thickness variations, so it is essential to create samples with uniform and repeatable layer thicknesses. We report the growth and characterization of epitaxial Dy/Y multilayer samples and our optimization of the growth temperature to produce samples with well-defined superlattice Bragg peaks in high-angle x-ray diffraction.
Funded by US-DOE through DE-FG02-08ER46499 and research at Oak Ridge National Laboratory’s High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.