Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 6: Ultrafast magnetism I
MA 6.4: Vortrag
Montag, 12. März 2018, 10:15–10:30, EB 407
Computational investigation of ultrafast magnetization dynamics; ferromagnets vs antiferromagnets — •Unai Atxitia1, Severin Selzer2, Tobias Birk2, Marcel Strohmeier2, and Ulrich Nowak2 — 1Department of Physics, Freie Universität Berlin, D-14195 Berlin, Germany — 2Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
The speed of switching between two stable magnetic states has become a major bottleneck for future advancement of magnetic-based information technologies. Magnetization dynamics in antiferromagnets (AFM) are proposed to be considerably faster than their ferromagnetic (FM) counterparts. In FM, thermal effects can drive magnetization dynamics in a wide range of timescales, from femtosecond laser induced sub-picosecond magnetic order relaxation to the slower thermally activated magnetic reversal in nanoparticles. Thermally induced magnetization dynamics in AFM are rather unknown. Here, we investigate the differences between AFM and FM in the thermally induced magnetization dynamics by means of computer simulations based in atomistic spin models. First, we investigate the superparamagnetic limit. Surprisingly, we find that in AFM nanoparticles, switching time is faster than in FM, even if the energy barrier is the same. Second, sub-picosecond heat induced demagnetization; in AFM is up to one order of magnitude faster than in FM. Interestingly, the subsequent remagnetization process to the initial state could also be up to two orders of magnitude faster than in FM. These findings have strong implications for ultrafast control of magnetic states in antiferromagnets.