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MA: Fachverband Magnetismus
MA 31: Poster II
MA 31.16: Poster
Mittwoch, 19. März 2025, 17:00–19:30, P1
Laser-induced magnetostriction in Gd, Tb and Dy probed by UXRD — •Florian Baltrusch1, Alexander von Reppert1, Steffen P. Zeuschner1, Maximilian Mattern1, Matthias Rössle2, Florin Boariu2, Karine Dumesnil3, and Matias Bargheer1,2 — 1Institut für Physik und Astronomie, Universität Potsdam, Potsdam, Germany — 2Helmholtz-Zentrum Berlin, Berlin, Germany — 3Institut Jean Lamour, Universite Lorraine, Nancy, France
In ultrafast X-ray experiments, we compare the laser-induced magnetostriction in Gd, Tb and Dy upon femtosecond laser excitation at temperatures above and below the magnetic ordering temperatures. These rare earths exhibit giant spontaneous magnetostriction and consequently negative thermal expansion (NTE). The coupling between magnetic order and the lattice below the Curie temperature leads to a competition between the expansive stresses from electrons and phonons and the contractive stress due to magnetic order. Thus, upon femtosecond laser excitation, the ultrafast dynamics show a variety of interesting results, such as transforming a typical bipolar strain wave into a unipolar pulse. By comparing equilibrium thermal expansion and heat capacities, we separate electronic, phononic, and magnetic stress contributions using an extended Grüneisen model based on energy densities in each of the three subsystems. This enables fitting ultrafast strain dynamics and identifying subsystem coupling constants.
Keywords: magnetism; magnetostriction; spin-lattice interaction; rare-earth metals; ultrafast