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MA: Fachverband Magnetismus
MA 42: Posters Magnetism I
MA 42.24: Poster
Mittwoch, 18. März 2020, 15:00–18:00, P3
The role of coherent and incoherent phonons for the excitation of standing spin waves — •Steffen Peer Zeuschner1,2, Marwan Deb1, Alexander von Reppert1, Jan-Etienne Pudell1, Elena Popova3, Niels Keller3, Matthias Rössle2, Marc Herzog1, and Matias Bargheer1,2 — 1Institut für Physik und Astronomie, Universität Potsdam, 14476 Potsdam, Germany — 2Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, BESSY II, 12489 Berlin, Germany — 3Groupe d'Etude de la Matiére Condensée (GEMaC), CNRS UMR 8635, Université Paris-Saclay, 78035 Versailles, France
We present ultrafast X-ray diffraction (UXRD) and magneto-optical Kerr-effect (MOKE) measurements of the ferrimagnetic insulator bismuth-doped yttrium iron garnet (Bi:YIG). We compare the response of direct optical excitation of a Bi:YIG thin film with femtosecond laser pulses to the indirect excitation mediated by a thin metal transducer. In both cases, a coherent phonon wavepacket instantly traverses the Bi:YIG layer as a result of ultrafast deposition of energy. The main difference are incoherent phonons which are stimulated immediately inside the directly excited Bi:YIG layer but diffuse into the Bi:YIG layer on the timescale of hundreds of picoseconds after exciting the metal transducer. We analyze the response of the magnetic system to the coherent and incoherent phonons in the form of ultrafast demagnetization and standing spin waves (SSW). Via the quantitative assessment of the strain we disentangle the combination of heat and sound in the context of ultrafast stimulation of SSWs.