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O: Fachverband Oberflächenphysik

O 16: Magnetic Excitations: from surfaces down to adatoms (jointly with MA)

O 16.1: Topical Talk

Montag, 11. März 2013, 15:00–15:30, H23

Tailoring magnetic excitations in low-dimensional ferromagnets — •Khalil Zakeri Lori — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany

We present a summery of our recent results on elementary magnetic excitations (magnons) in ultrathin ferromagnets. Terahertz magnons in ultrathin Fe(100), Fe(110) and Fe(111) films, grown on different surfaces, are probed by means of spin-polarized high resolution electron energy-loss spectroscopy. The key properties of magnons such as their dispersion relation and lifetime are measured over the entire Brillouin zone. It is demonstrated that these properties depend strongly on the atomic structure of the films as well as the degree of electronic hybridization with the substrate. We discuss how the complexity of the electronic structure, degree of electronic hybridization and the contribution of different orbitals to the exchange interaction can lead to unexpected behavior of magnon energies. The lifetime of terahertz magnons is found to be a few tens of femtoseconds at low wave vectors, which reduces significantly as the wave vector approaches the Brillouin zone boundary. Based on our results we comment on the damping mechanism of terahertz magnons. Finally, we introduce a way of tailoring the properties of terahertz magnons by engineering the electronic structures.