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HL: Fachverband Halbleiterphysik
HL 38: Focus Session: Magnon Polarons – Magnon-Phonon Coupling and Spin Transport (joint session MA/HL)
HL 38.4: Vortrag
Mittwoch, 18. März 2020, 11:00–11:15, HSZ 04
Formation of magnon polarons in ferromagnetic nanogratings — •Felix Godejohann1, Alexey Scherbakov1,2, Serhii Kukhtaruk1,3, Alexander Poddubny2, Dmytro Yaremkevych1, Mu Wang5, Achim Nadzeyka4, Dmitri Yakovlev1,2, Andrew Rushforth5, Andrey Akimov5, and Manfred Bayer1,2 — 1Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany. — 2Ioffe Inst., RAS, St. Petersburg, Russia — 3Dept. of Theo. Phys., V.E. Lashkaryov Inst. of Semiconductor Phys., Kyiv, Ukraine — 4Raith GmbH, 44263 Dortmund, Germany — 5School of Phys. and Astronomy, Univ. of Nottingham, UK
In our time-resolved experiments with ferromagnetic nanogratings (NGs), the formation of coherent magnon polarons is confirmed by direct evidence of the avoided crossing effect, as well as by several bright indirect manifestations. The NGs have been produced by focused ion beam milling into a 105 nm-thick Fe0.81Ga0.19 film. They have a lateral period of 200 nm and consist of parallel grooves of 100-nm width and 7-21 nm depth milled along the [100]-crystallographic direction. We perform transient magneto-optical measurements in a conventional pump-probe scheme with micron spatial resolution, where the femtosecond pump pulse excites the NGs, while the probe pulse serves to detect coherent lattice and magnetic responses. Using an external magnetic field, the magnon modes can be brought into resonance with the localized phonon modes of the NG resulting in the formation of magnon polarons, where the coupling strength is determined by the spatial overlap of the interacting modes.