Light-induced ultrafast magnetization dynamics in YIG:Co films
We report on large-amplitude magnetization precession in a ferrimagnetic cobalt-substituted yttrium iron garnet (YIG:Co) thin film through excitation by linearly polarized 100 fs laser pulses. The deviation of the magnetization from its initial equilibrium position achieved via a photoinduced magnetic anisotropy (PMA) effect was as high as 20deg. we observed significant changes (up to 2 GHz, that is a 50% change from the initial value) of the precession frequency as a function of light polarization, suggesting the feasibility of subpicosecond frequency modulation [1].
To study the effect of intense femtosecon laser pulses on garnet material, we carried out time-resolved measurements at room temperature using a magneto-optical pump-probe setup in Faraday configuration.
Pronounced light-induced oscillations are observed with an amplitude and frequency dependent on the applied field. The experimental observations and model allow us to conclude that femtosecond optical excitation of YIG:Co gives rise to a strong nonthermal PMA, which is most noticeable at low applied fields [2]. For example, at 0.4 kG, we obtained a deviation angle for the magnetization of 20o at a pump intensity of 60 mJ/cm2.
- F. Atoneche, A.M. Kalashnikova, A.V. Kimel, A. Stupakiewicz, A. Maziewski, A. Kirilyuk, and Th. Rasing, “Large ultrafast photoinduced magnetic anisotropy in a cobalt-substituted yttrium iron garnet”, Phys. Rev. B 81, 214440 (2010).
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A Stupakiewicz, M Pashkevich, A Maziewski, A Stognij, N Novitskii, “Spin precession modulation in a magnetic bilayer” Applied Physics Letters 101 (26), 262406 (2012).