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PLV: Plenarvorträge

PLV V

PLV V: Plenary Talk

Wednesday, March 19, 2025, 08:30–09:15, H1

Ultrafast magnetism- terra incognita beyond the classical approximations — •Alexey Kimel — Radboud University, Nijmegen, The Netherlands

While the conventionally accepted Curie-Neumann’s principle states that "the symmetries of the causes are to be found in the effects" [1], in ultrafast magnetism the principle fails and magnetization dynamics becomes counter-intuitive. We will demonstrate that ultrafast (sub-100 ps) heating with the help of ultrashort laser pulses causes magnetization reversal without any magnetic fields [2], laser-induced spin dynamics is strongly non-linear, where new channels of spin-lattice interaction open-up [3,4], the principle of superposition fails i.e. 1+1>2 [5] and the approximation of macrospin is no longer adequate [6].

[1] P. Curie, J. Phys. Theor. Appl., 393-415(1894).

[2] T.A. Ostler et al, Ultrafast heating as a sufficient stimulus for magnetization reversal in a ferrimagnet, Nature-Communications 3, 666 (2012).

[3] E. A. Mashkovich et al, THz light driven coupling of antiferromagnetic spins to lattice, Science 374, 1608-1611 (2021).

[4] T. W. J. Metzger et al, Magnon-phonon Fermi resonance in antiferromagnetic CoF2, Nature Communications 15, 5472 (2024).

[5] T. G. H. Blank et al, Empowering control of antiferromagnetic spins by THz spin coherence, Phys. Rev. Lett. 131, 096701 (2023).

[6] F. Formisano et al, Coherent THz spin dynamics in antiferromagnets beyond the approximation of the Neel vector, APL Mater. 12, 011105 (2024).

Keywords: ultrafast magnetism; antiferromagnets; spin dynamics; magneto-optics; THz spectroscopy