AVS 51st International Symposium
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI-ThA

Invited Paper MI-ThA7
Excitation of Microscopic Spin Waves in Ultrathin Films by Spin-Polarized Electron Energy Loss Spectroscopy

Thursday, November 18, 2004, 4:00 pm, Room 304A

Session: Molecular Spintronics and Dynamics
Presenter: M. Etzkorn, Max Planck Institute of Microstructure Physics, Germany
Authors: R. Vollmer, Max Planck Institute of Microstructure Physics, Germany
W. Tang, Max Planck Institute of Microstructure Physics, Germany
M. Etzkorn, Max Planck Institute of Microstructure Physics, Germany
P.S.A. Kumar, Max Planck Institute of Microstructure Physics, Germany
H. Ibach, Institute for Surfaces and Interfaces, Germany
J. Kirschner, Max Planck Institute of Microstructure Physics, Germany
Correspondent: Click to Email
The properties of long wavelength spin waves have been investigated since decades by ferromagnetic resonance (FMR), Brillouin light scattering (BLS) and more recently by time domain optical techniques. The properties of these spin waves are determined largely by macroscopic and static quantities like the magnetization and anisotropy energies. In bulk materials inelastic magnetic neutron scattering can be used to measure microscopic spin waves with wavelength of atomic dimensions. We have shown recently that spin polarized electron energy loss spectroscopy (SPEELS) can be used to study these microscopic spin waves in ultrathin films up to the surface Brillouin zone boundary@footnote 1@. Up to now we have investigated ultrathin films of fcc Co, hcp Co, fcc Fe, fcc Fe, and bcc Fe on various substrates. In most cases the spin wave excitation can be observed as well pronounced peak in the loss spectrum. In this case, the acoustic spin wave branch of the surface spin wave mode can be described surprisingly well by a simple nearest-neighbor Heisenberg model. Nevertheless, the spectra indicate the itinerant character of the spin waves as discussed in Ref.@footnote 2@. The acoustic branch is significantly broadened and no clear indication of an optical mode (expected from a Heisenberg model) could be observed up to now. The spin wave peaks are visible in the SPEEL spectrum only for low (<10 eV) energies of the incident electrons. @FootnoteText@ @footnote 1@ R. Vollmer, M. Etzkorn, P.S. Anil Kumar, H. Ibach, and J. Kirschner, Phys. Rev. Lett. 91, 147201 (2003).@footnote 2@ A. T. Costa, Jr., R. B. Muniz, D. L. Mills, Phys. Rev. B 69, 064413 (2004).