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MA: Fachverband Magnetismus
MA 21: Ultrafast Magnetization II
MA 21.9: Vortrag
Dienstag, 17. März 2020, 11:45–12:00, HSZ 101
Elucidating the mechanism for all-optical switching by tuning the femtosecond pulses into the infrared wavelength range — Robin John1, •Jakob Walowski1, Cai Müller2, Marco Berritta3, Deninse Hintzke4, Oksana Chubykalo-Fesenko5, Tiffany Santos6, Henning Ulrichs7, Ritwik Mondal4, Peter Oppeneer3, Ulrich Nowak4, Jeffrey McCord2, and Markus Münzenberg1 — 1Greifswald University, Greifswald, Germany — 2Kiel University, Kiel, Germany — 3Uppsala University, Uppsala, Sweden — 4Konstanz University, Konstanz, Germany — 5CSIC, Madrid, Spain — 6Western Digital, San Jose, CA, United States — 7Göttingen University, Göttingen, Germany
The energy transfer from electrons to spins upon laser excitation is the basis for the response dynamics, it determines the speed of ultrafast magnetization. In FePt nanoparticles, a material developed for heat-assisted magnetic recording, all-optical writing has been demonstrated by Lambert et al. in Science 2014. In the current understanding of the interaction of ultrafast excitation and heating, the influence of magnetic dichroism MCD and the presence of the inverse Faraday effect IFE jointly work as forces causing magnetization reversal.
We calculate the switching rates of the individual FePt nanoparticles in ab-initio calculations of the optical effects (IFE and MCD induced heating) included in thermal modelling, which provide switching rates for the ensembles. This theoretical description allows us to optimize the required number of shots to write the magnetization in experiments and optimize the process by tuning the laser fluence and wavelength.