Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 16: Spin Dynamics: Magnetic relaxation and Gilbert Damping
MA 16.2: Vortrag
Montag, 20. März 2017, 17:45–18:00, HSZ 401
Lifetime of terahertz magnons in ultrathin ferromagnets: Temperature effects — Huajun Qin1, •Khalil Zakeri Lori2,1, Arthur Ernst1, and Juergen Kirschner1 — 1Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany — 2Heisenberg Spin-dynamics Group, Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe, Germany
Utilizing spin-polarized high resolution electron energy loss spectroscopy we investigate the temperature dependence of high-energy (terahertz) magnons, excited in an ultrathin ferromagnet. Both the energy and lifetime of terahertz magnons are measured as a function of temperature and across the magnetic transition temperature TC. Similar to the magnons’ energy, their lifetime decreases with temperature. The observed temperature-induced damping of terahertz magnons is discussed in terms of multi-magnon scattering mechanism. Our results indicate that the damping resulted from this mechanism can be comparable to the intrinsic Landau damping of the system. We demonstrate that although at TC terahertz magnons are affected by different damping mechanisms, they still behave as well-defined collective excitations. We argue that the effects associated with the collective properties of terahertz magnons should eventually sustain at TC and even beyond that.