Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 14: Magnetization / Demagnetization Dynamics II

MA 14.6: Vortrag

Montag, 20. März 2017, 16:30–16:45, HSZ 401

Inhomogeneous laser induced ultrafast magnetization dynamics at Co/Cu(001) films analyzed by interface-sensitive nonlinear magneto-optics — •Jinghao Chen, Andrea Eschenlohr, Jens Wieczorek, Shunhao Xiao, Alexander Tarasevitch, and Uwe Bovensiepen — Fakultät für Physik, Universität Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany

A femtosecond laser pulse drives metallic ferromagnets into non-equilibrium and causes an ultrafast quenching of the magnetization [1]. The optically excited magnetization dynamics is analyzed via time-resolved optical magnetization-induced second harmonic generation (mSHG). In this work we report a systematic thickness dependent study of Co/Cu(001) in the Co thickness range from 0.4 to 10 nm. We identify two interface contributions and apply a simple model to separate the contributions from the vacuum/Co und Co/Cu interfaces to the total SHG yield. The transient magnetization dynamics of the Co film in the first 300 fs is dependent on the film thickness. We find that for Co film thickness d < 3 nm the vacuum/Co interface is more strongly demagnetized than the Co/Cu interface, for d > 3 nm i.e. above the spin dependent inelastic mean free path [2], the Co/Cu interface has a stronger demagnetization than the vacuum/Co interface, which implies that the majority spins at the interface escape into the conducting substrate [3].

[1] E. Beaurepaire et al., Phys. Rev. Lett. 76, 4250 (1996) [2] V. P. Zhukov et al., Phys. Rev. B 73, 125105 (2006) [3] J. Chen et al., http://arxiv.org/abs/1608.03842.