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MA: Fachverband Magnetismus

MA 63: Spin: Transport, Orbitronics and Hall Effects III

MA 63.9: Vortrag

Freitag, 20. März 2020, 11:45–12:00, HSZ 403

Effective damping of terahertz spin-wave modes in iron — •Liane Brandt¹, Niklas Liebing¹, Ilya Razdolski², Roman Verba³, Vasyl Tyberkevych⁴, Andrei Slavin⁴, Georg Woltersdorf¹, and Alexey Melnikov¹ — ¹Martin Luther University Halle-Wittenberg, Institute of Physics, Halle (Saale), Germany — ²Fritz Haber Institute of the Max Planck Society, Department of Physical Chemistry, Berlin, Germany — ³Institute of Magnetism, Kyiv, Ukraine — ⁴Oakland University, Department of Physics, Rochester, USA

Recently, we have demonstrated the excitation of perpendicular standing spin waves (PSSW) in Fe/Au/Fe tri-layers studied by the time-resolved magneto-optical Kerr effect in a back pump-front probe scheme [1]. This high-frequency spin dynamic is driven by interface-confined spin transfer torque exerted by 250 fs-short spin current pulses generated in the optically excited emitter Fe layer [2]. The frequency of the PSSWs is tuned up to 2.5 THz by continuously reducing the thickness of collector Fe layer from 17 to 1 nm.

By analyzing the effective damping of the PSSW modes we observe an increase by two orders of magnitude in effective damping with increasing wave number. While the Gilbert damping is independent on the wave number, we can describe the increase in effective damping by the k-dependent spin diffusion term. Additional effects due to interfaces, defects in the volume and spin pumping appear to be small.

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

[2] A. Alekhin et al., PRL 119, 017202 (2017)