Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 50: Poster II

MA 50.46: Poster

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

Spin pumping in YIG/Pt bilayer — •Markus Härtinger¹, Sibylle Meyer², Stephan Geprägs², Matthias Opel², Hans Huebl², Sebastian T.B. Goennenwein², Christian Back¹, and Georg Woltersdorf¹ — ¹Department of Physics, Universität Regensburg, 93040 Regensburg, Germany — ²Walter-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany

Spin pumping adds an additional damping mechanism to the instinsic damping propierties of a magnetization precession by emission of an angular momentum flow. When the latter is relaxed, e.g. in a material with large spin orbit scattering like Pt, the spin current is efficiently damped, resulting in an increased FMR linewidth. Here we report on this effect in a bilayer of the insulating ferrimagnet Yttrium Iron Garnet (YIG) and platinum (Pt). The samples consist of ultrathin epitaxial YIG layers grown by pulsed laser deposition on GGG(111) (Gadolinium Gallium Garnet) substrates. The platinum capping layers are deposited in-situ. We have determined the magnetic properties by performing ferromagnetic resonance (FMR) measurements on YIG layers as well as on bilayer YIG/Pt samples in a frequency range from 2 to 20 GHz. In the pure YIG samples we find very narrow resonance lines corresponding to a Gilbert damping constant of approximately α=0.001. Due to the spin pumping an additional platinum layer on top of the YIG samples results in a significant broadening of the FMR linewidth proportional to the microwave frequency. In order to substantiate this we measured the platinum and YIG thickness dependence of this additional damping.