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MA: Fachverband Magnetismus
MA 9: Spin Excitations/Spin Torque
MA 9.2: Talk
Monday, March 16, 2015, 15:45–16:00, H 0112
Electron energy loss spectroscopy of spin waves in ultrathin films of cobalt on Cu(111) and W(110) — •Eugen Michel1,2, Harald Ibach1,2, and Claus M. Schneider1,2 — 1Peter-Grünberg-Institut, Forschungszentrum Jülich, 52425 Jülich, Germany — 2Jülich Aachen Research Alliance, Germany
For ultrathin fcc Co/Cu(100) films the dispersion of standing spin wave modes as function the film thickness was shown to be a sensitive probe for the layer dependence of layer exchange coupling constants [1]. We extend the method to hcp Co films grown on Cu(111) and W(110). In addition to the acoustic spin wave we observe up to two standing spin wave modes in films with thicknesses ranging from 2 to 8 atomic layers and wave vectors between 1.6 - 5 1/nm. We find that the layer-dependent dispersion curves obtained for both substrates are consistent with each other when the island growth of Co on Cu(111) is taken into account. Compared to fcc cobalt films on Cu(100) the standing spin waves have a substantially lower energy, which is consistent with the lower number of nearest neighbor interactions between subsequent layers. The results are discussed within the framework of a Heisenberg model with modified coupling constants at surface and interface.
[1] J. Rajeswari et al., Phys. Rev. Lett. 112, (12), pp 127202 (2014)