Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 26: Spin Dynamics / Spin -Torque II

MA 26.9: Vortrag

Donnerstag, 28. Februar 2008, 16:45–17:00, EB 301

Determination of the magnon dispersion of ferromagnets on the nanometer scale — •Nicolai Urban, Timofey Balashov, Albert F. Takacs, and Wulf Wulfhekel — Physikalisches Institut, Universität Karlsruhe (TH), Wolfgang Gaede Str. 1, 76131 Karlsruhe

We studied the dispersion of magnons in thin ferromagnetic Co films on Cu(100) using inelastic tunneling spectroscopy at 4K. By an interaction between the tunneling electrons and the spin-polarized electron sea of the films, magnons can be excited. Due to the finite thickness of the films, a series of standing magnons quantized perpendicular to the plane evolves. From the film thickness and the order of the standing mode, the magnon momenta can be determined while the energy is given by the position of the extrema in the inelastic tunneling spectra. The obtained dispersion curve agrees well with neutron scattering data and with ab-initio calculations within the whole Brillouin zone [1]. This experimental method allows to determine excitation energies and magnon dispersions of magnetic materials on the nanometer scale.

[1] M. Pajda et al., Phys. Rev. B. 64, 174402 (2001).