Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 55: Poster II
MA 55.25: Poster
Freitag, 4. April 2014, 10:30–13:30, P2
Determination of the Spin Hall Angle using Time and Spatially Resolved Ferromagnetic Resonance in Metallic Bi-layers — •Martin Decker1, Christian Back1, and Georg Woltersdorf2 — 1Department of Physics, University of Regensburg, 93053, Germany — 2Department of Physics, MLU Halle-Wittenberg, 06099, Germany
We investigate the spin Hall effect in different ferromagnet(FM)/normal(NM) metal bi-layers and determine the spin Hall angle of the normal metal. Ferromagnetic Resonance (FMR) measurements are performed on a micro-structured bi-layer. The linear response of the magnetization to ac magnetic fields in the GHz range, created by a microstructured coplanar waveguide, is measured using time and spatially resolved Kerr microscopy. A dc current is applied to the bi-layer and causes the injection of a spin current from the normal metal (NM) into the ferromagnet (FM). This spin current induces a spin torque acting on the magnetization which in turn modifies the linewidth of the FMR signal. Measurements of the linewidth as a function of the applied current provide access to the spin Hall angle of the NM [1, 2]. In contrast to the widely used technique of spin pumping, our method also allows to study normal metals that do not have a large spin mixing conductance. We determine the Spin Hall angle of Platinum, Gold and Tantalum, using Permalloy as a ferromagnet.
[1] K. Ando et al., PRL 101, 036601 (2008).
[2] V.E. Demidov et al., APL 99, 172501 (2011).