Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 14: Magnetization / Demagnetization Dynamics II
MA 14.9: Vortrag
Montag, 20. März 2017, 17:15–17:30, HSZ 401
Direct observation of dipolar-exchange magnon and phonon spectra in arbitrary magnetized yttrium-iron-garnet films — •Dmytro A. Bozhko1,2, Philipp Pirro1, Halyna Musiienko-Shmarova1, Ihor I. Syvorotka3, Burkard Hillebrands1, and Alexander A. Serga1 — 1Fachbereich Physik and Landesforschungszentrum OPTIMAS, TU Kaiserslautern, Germany — 2Graduate School Materials Science in Mainz, Germany — 3Department of Crystal Physics and Tehnology, SRC “Carat”, Ukraine
We report on results of the experimental investigation of thermal spectra of dipolar-exchange magnons and transversal acoustic phonons in an obliquely magnetized yttrium-iron-garnet (YIG) thin film. Magnons and phonons propagating along the projection of the bias magnetic field H→ (H=2500 Oe) on the film surface were probed by wavevector-resolved Brillouin light scattering spectroscopy. The YIG film of 5.6 µm thickness was grown in the (111) crystallographic plane on a gadolinium-gallium-garnet substrate by liquid-phase epitaxy. It has been found that in the case of oblique magnetization the spectrum of long-wavelength dipolar magnons splits into forward and backward spin-wave modes with positive and negative group velocities, respectively. With decrease of the magnon wavelength, these modes merge into a single exchange branch. This transition from the dipolar to the exchange regimes, which is still not described by existing theoretical models, is analyzed and discussed. The work is supported by the DFG within the SFB/TR 49.