Physikalische Chemie - Direktor: Prof. Dr. Martin Wolf
Department Seminar
Host: R. Ernstorfer

Monday, November 12, 2018, 11:00 am
PC Seminar Room, G 2.06, Faradayweg 4
Dr. Unai Atxitia
Quantum many-body theory, quantum information theory, and quantum optics, Department of Ühysics, Freie Universität Berlin
Phenomenology of the ultrafast spin dynamics 
driven by femtosecond laser pulses
The interest for ever faster control of the magnetic order lies in the tremendous technological impact spintronic devices already have today and possibly hold for future data storage and processing technology. Here, the information is contained in the orientation of a magnetic domain. Simple Oersted fields are used to manipulate those magnetic states. However, generation of magnetic fields at the nanoscales is challenging, and therefore writing magnetic data at the nanoscale is currently limited to about 1 ns (10-9 s).
A promising way to manipulate and control magnetic states is the use of femtosecond laser pulses [1], a broad field of research named ultrafast spin dynamics. However, many aspects of the ultrafast spin dynamics are not fully understood yet. In this talk I give a brief overview on the current state of ultrafast spin dynamics. The most relevant scientific findings of the past decades will be presented and their underlying physical mechanisms will be discussed on the basis of phenomenological models. This includes the magnetic response of the transition metal Ni [2] and rare earth Gd [3] to femtosecond laser pulses, and its relation to the unique picosecond magnetic switching of transition metal rare earth alloy Gd(FeCo) [4].
[1] Beaurepaire, et al. Phys. Rev. Lett. 76, 4250 (1996).
[2] Tengdin, et al. Sci. Adv. 4, eaap9744 (2018); U. Atxitia et al. Phys. Rev. B 81, 174401 (2010).
[3] B. Frietsch et al. Nature Communication 6, 8262 (2015); M. Sultan, U. Atxitia, et al. Phys. Rev. B 85, 184407 (2012).
[4] T. A. Ostler et al. Nature Communication 3, 666 (2012).