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MA: Fachverband Magnetismus

MA 11: Ultrafast magnetism II

MA 11.8: Vortrag

Montag, 12. März 2018, 17:00–17:15, EB 407

All-optical magnetization switching of FePt nanoparticles by fs laser pulses — •D. Hinzke¹, T. Knippenberg¹, M. Berritta², R. Mondal^1,2, R. John³, J. Walowski³, C. Müller⁴, J. McCord⁴, P. Oppeneer², M. Münzenberg³, and U. Nowak¹ — ¹Universität Konstanz — ²Uppsala University — ³Universität Greifswald — ⁴Universität Kiel

Helicity-dependent all-optical switching (HD-AOS) caused solely by the effect of an ultrafast laser pulse was not only demonstrated for ferrimagnets [1] but also for layered, synthetic ferrimagnets [2] and simple ferromagnets [3]. We study HD-AOS in FePt nanograins numerically by using a complete multiscale model [4]. In our simulation it is possible to distinguish thermal and non-thermal contributions to the HD-AOS.

One of our findings is that a principle difference between magnetic circular dichroism (MCD) and inverse Faraday effect (IFE) assisted switching is the helicity-dependent heating. MCD only leads to a stochastic demagnetization process and, therefore, deterministic single-shot magnetization switching is not possible. On the contrary, an additional magnetization contribution is provided by the IFE that supports deterministic magnetization reversal. We investigate the switching probability of single FePt grains as a function of laser power and number of consecutive laser shots.

[1] K. Vahaplar et al, Phys. Rev. Lett. 103, 117201 (2009) [2] S. Mangin et al, Nat. Materials 13, 287 (2014) [3] C.-H. Lambert et al, Science (345), 1337 (2014) [4] R. John et al, Sci. Rep. 7, 4114 (2017)