Berlin 2018 – scientific programme

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MA: Fachverband Magnetismus

MA 6: Ultrafast magnetism I

MA 6.8: Talk

Monday, March 12, 2018, 11:30–11:45, EB 407

A micromagnetic model for ultrafast spin current-driven magnon dynamics — •Henning Ulrichs¹ and Ilya Razdolski² — ¹I. Physical Institute, Georg-August University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — ²Physical Chemistry Department, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany

Recent experimental reports have demonstrated that optically induced femtosecond spin currents can excite coherent magnon dynamics in the THz frequency range.[1,2] In this talk I will discuss a simple micromagnetic model for this process. The basic ingredient of this practically 1d model is a Slonczewski-like spin-transfer torque term. With this, we can reproduce the salient features of the experiments presented in reference [1]. Furthermore, the model provides insight into the factors which govern the spin wave mode-specific excitation efficiency. Lastly, I will discuss results for a collinear spin injection geometry. Our modelling shows that then, a thermally occupied magnon ensemble can be heated or cooled on fs time-scales. HU acknowledges financial support by the DFG within project A06 of the SFB 1073.

[1] I. Razdolski et al., Nat. Comm. 8, 15007 (2017)

[2] M.L.M. Lalieu, P.L.J. Helgers, and B. Koopmans, Phys. Rev. B, 96, 014417 (2017)