Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 91: [MA] Poster II
O 91.9: Poster
Friday, March 30, 2012, 11:00–14:00, Poster A
Spin calorics in ferromagnetic Heusler alloys on semiconductors — •Yori Manzke, Farshchi Rouin, Ramsteiner Manfred, and Jens Herfort — Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
Recently, a spin-based counterpart to the Seebeck effect (SE) has been discovered in various ferromagnetic systems, which can potentially serve to generate spins from waste heat in future spintronic devices. In contrast to the SE, where a temperature gradient leads to a charge potential difference across a material, in the spin-based version (or SSE) a thermal gradient induces a "spin voltage", i.e. a chemical potential difference due to a spin imbalance in the material. However, the SSE is difficult to isolate due to other magnetothermal effects, and special experimental criteria must be met to eliminate such artifacts. Here, we report clear evidence of spin-induced voltages across Pt strips deposited on epitaxially grown Fe3Si/GaAs hybrid structures. The Pt strips are intended to convert spin currents from the Fe3Si layer into measurable voltages via the inverse spin Hall effect, while also eliminating magnetothermal artifacts. These voltages depend on the magnetization of the Fe3Si layer and appear as a consequence of thermal gradients across the sample. Nonetheless, the spatial and temperature dependences of the spin voltages observed in our samples fundamentally differ from those of other materials systems for which the SSE has been reported. Therefore, these findings may be crucial for the understanding of the SSE.