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MA: Fachverband Magnetismus
MA 38: Ultrafast Magnetization Effects II
MA 38.3: Vortrag
Mittwoch, 11. März 2026, 15:30–15:45, POT/0361
Probing ultrafast dynamics of artificial antiferromagnets by soft-x-ray diffraction — •Jasmin Jarecki1, Martin Borchert1, Stefan Eisebitt1, 2, and Daniel Schick1 — 1Max-Born-Institut für Nichtlineare Optik & Kurzzeitspektroskopie, Berlin, Germany — 2Institut für Optik & Atomare Physik, TU Berlin, Germany
Ordering phenomena in solids encode key information about microscopic interactions and subsystem coupling. In magnetic materials, magnetic and structural order can be strongly coupled, yet the corresponding periodicities may exhibit different characteristic lengths. This calls for methods capable of simultaneously probing lattice and spin degrees of freedom to disentangle phonon and spin dynamics.
Using on- and off-resonant ultrafast x-ray diffraction (UXRD) in the soft-x-ray regime, we investigate the coupled structural and magnetic dynamics of a Fe/Cr superlattice (SL), an artificial antiferromagnet in which adjacent Fe layers adopt alternating magnetization directions for the chosen Cr spacer thickness. By tracking the structural and magnetic SL Bragg peaks, we study photon-energy- and fluence-dependent dynamics via their transient peak positions and intensities. While the structural peak shift and the magnetic peak intensity follow the expected behavior, the magnetic peak shift deviates markedly from the structural response and, in particular, does not exhibit the anticipated linear fluence dependence. These findings highlight the strong intercoupling between depth-dependent sample dynamics and depth-dependent probing, underscoring the need for careful analysis and modeling to reliably extract microscopic dynamics from UXRD.
Keywords: Soft X-ray diffraction; antiferromagnet; ultrafast magnetization dynamics; superlattice; pump-probe