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MA: Fachverband Magnetismus

MA 42: Posters Magnetism I

MA 42.12: Poster

Mittwoch, 18. März 2020, 15:00–18:00, P3

THz spin-wave generation in optically-driven acoustic resonators — •Dennis Meyer, Vitaly Bruchmann-Bamberg, Christopher Heins, Sina Ludewig, Vasily Moshnyaga, and Henning Ulrichs — I. Physical Institute, Georg-August University Göttingen, 37077 Göttingen, Germany

Ultrafast optically-driven coherent THz spin wave sources are of crucial importance for high frequency spintronic applications. However, a monochromatic coherent spin-wave generation for frequencies f=0.1−6 THz is hard to achieve using optical methods, which produce rather incoherent or non-monochromatic spin-waves. Magneto-elastic coupling, usually viewed as an undesirable dissipation channel in spintronics, was recently shown to generate spin currents and coherent magnetic oscillations in the low GHz regime. Such experiments, utilizing microwave radiation, are practically restricted to frequencies less than 10 GHz. We propose a novel design to generate THz spin waves by laser excitation of an acoustic nanocavity. The idea is to apply a fs-laser pulse to generate a spectrally broad stress pulse in a metallic transducer layer (β-W or Pt) that passes a ferromagnetic layer (e.g. La_0.7Sr_0.3MnO₃ or CoFeB) featuring significant magneto-elastic coupling. Finally, it reaches a superlattice structure (e.g. LaMnO₃/SrMnO₃), which acts as a frequency selective Bragg mirror for phonons. By matching the dispersion of magnons and phonons, energy transfer from the phonon into a magnon mode occurs. We acknowledge financial support by the DFG within project A02 of the CRC 1073 Atomic scale control of energy conversion.