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AM: Magnetismus

AM 1: Spektroskopie I & II

AM 1.11: Talk

Monday, March 26, 2001, 12:30–12:45, S 5.2

Observation of Spinwaves in a Magnetic Superlattice by inelastic Neutron Scattering — •A. Schreyer¹, A. Wildes², W. Schmidt², C.F. Majkrzak³, and J. Kwo⁴ — ¹Institut für Experimentalphysik (Festkörperphysik), Ruhr-Universität Bochum, 44780 Bochum — ²Institut Laue Langevin, BP 156, 38042 Grenoble, Frankreich — ³National Institute of Standards and Technology, Gaithersburg, MD 20899, USA — ⁴Lucent Technologies, Bell Labs, Murray Hill, NJ 07974, USA

So far only light scattering and ferromagnetic resonance techniques have been used to extract information on magnetic excitations in magnetic layered systems. However, only inelastic neutron scattering (INS) can access wide portions of the Brillouin zone allowing the determination of spin wave dispersion curves. To overcome the lack of signal from thin film samples, a rare-earth system with a large magnetic scattering length was chosen and the amount of material was increased by growing a superlattice with 350 bilayers of Dy/Y. We present the first successful INS measurements on a magnetic superlattice, yielding a bulk-like acoustic magnon dispersion curve in a folded Brillouin zone. The latter effect is due to the superlattice periodicity which is not present in bulk. Having demonstrated that it is now possible to investigate spin wave dispersion curves at least in certain magnetic thin film systems, limitations as well as future perspectives and applications will be discussed.