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Regensburg 2019 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: Magnetism Poster A

MA 15.54: Poster

Dienstag, 2. April 2019, 10:00–13:00, Poster E

Picosecond Strain Dynamics driven by Ultrafast Demagnetization in Dysprosium — •Alexander von Reppert1, Jan-Etienne Pudell1, Steffen Zeuschner1,2, Karine Dumesnil3, and Matias Bargheer1,21Institut für Physik und Astronomie, Universität Potsdam, Potsdam, Germany — 2Helmholtz-Zentrum Berlin, Berlin, Germany — 3Institut Jean Lamour (UMR CNRS 7198), Université Lorraine, Nancy, France

We investigate the effects of the ultrafast demagnetization on the picosecond strain pulses launched in the highly magnetostrictive material Dysprosium (Dy). The laser-induced spin-disorder in heavy rare earth materials triggers a large negative stress, which dominates the c-axis lattice dynamics over the expansive stress that originates from (in)-coherent phonon excitations. The application of an in-plane B-field shifts the FM-AFM phase transition to higher temperatures and enhances the laser-induced contraction. By observing the coherent strain pulses spatially separated from the laser excited region, we eliminate the thermal background. We find strong changes to the characteristic bipolar strain pulse that is observed in the high temperature paramagnetic region, which we attributed to the depth dependent magnetostrictive stress in the inhomogeneously heated Dy layer. Our systematic exploration of the different magnetic phases characterizes to which extend the magnetostrictive stress in this material class can be used as a transducer for novel picosecond strain experiments with unipolar, or even inverted bipolar strain pulses.

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