Regensburg 2013 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 22: Poster II

DF 22.72: Poster

Freitag, 15. März 2013, 10:30–13:30, Poster D

Dynamical heating of ferrimagnetic structures in a wide range of magnetic fields — •Thomas Langner, Vitaliy Vasyuchka, Benjamin Jungfleisch, Andrii Chumak, Alexander Serga, and Burkard Hillebrands — Fachbereich Physik and Landesforschungszentrum OPTIMAS, TU Kaiserslautern, Erwin-Schroedinger-Str. 56, 67663 Kaiserslautern, Germany

Precessing magnetic moments can generate heat due to the decay of the precessional motion and the following transfer of energy into the phonon system. We placed a polycrystalline disc of yttrium iron garnet (YIG) in an external magnetic field and excited it with high power microwaves. The temperature of the disc was monitored with an infrared camera. Beside large heating at the ferromagnetic resonance (FMR) we show an unexpected heat generation with applied microwave frequencies around 3.5 GHz for magnetic fields between 0 and 200 Oe far below the FMR. In spite of practically the same absorption of microwaves the heating becomes smaller with higher magnetic field values in the mentioned range. The behavior can then be understood by resonant magnetic excitations of the grain structure inside the polycrystalline material. This assumption can be confirmed by a comparison to the behavior of a monocrystalline YIG structure and by an excitation of the polycrystalline sample by microwaves of higher frequencies.

Financial support by Deutsche Forschungsgemeinschaft within priority program SPP 1538 "Spin Caloric Transport" is gratefully acknowledged.