Hybrid systems consisting of epitaxial Heusler-alloy films on semiconductor structures for spin-caloric applications

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Spin-caloric transport phenomena have attracted significant interest in spintronics related research. Our proposal aims to explore different ferromagnetic Heusler-alloy films with regard to their usability for heat-induced spin transport as well as their potential to be implemented in spintronic semiconductor devices. Therefore, we investigate hybrid systems with the Heusler-alloy films grown by molecular beam epitaxy on semiconductor structures. Different Heusler alloy compositions will be evaluated with regard to their spin-Seebeck coefficients using the inverse spin Hall effect. Once the most promising compositions have been identified, we will study the transfer of spin and its accumulation from the ferromagnetic layer into the under-lying semiconductor structures. The resulting spin diffusion and transport in the semiconductor structures will be explored in lateral devices which allow for the non-local detection of spin diffusion. This approach sepa-rates drift currents from the spin diffusion path, and hence allows for an unambiguous demonstration of spin-related transport phenomena. Complementary to this all-electrical approach, optical Kerr rotation measurements will be used to verify the spatial distribution of a thermally induced spin accumulation. Furthermore, spin-light emitting diodes will be used to study the injection of spin currents into semiconductor structures. The fundamental mechanisms leading to spin-caloric transport phenomena will be addressed by a Raman spectroscopic study on the magnon and phonon systems in magnetic materials.