Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 50: HL Poster IV

HL 50.16: Poster

Thursday, March 15, 2018, 19:00–21:00, Poster B

Structural and spin transport studies of Co₂FeSi/MgO/GaAs heterostructures — •Georg Hoffmann, Manfred Ramsteiner, and Jens Herfort — Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany

Lateral spin valve (SV) structures allow the investigation of spin generation in semiconductors (SC) as well as spin transport and detection within one device. Regarding the spin-polarized contacts, Heusler alloys, such as Co₂FeSi (CFS), are of particular interest because of their possible half-metallic behavior. However, the properties of CFS/SC hybrid structures are often deteriorated by the diffusion of Fe and Co into the SC material. MgO interlayers at the CFS/SC interface have the potential to prevent the Fe and Co diffusion and to act as spin-filtering barriers. We studied CFS/MgO/GaAs hybrid structures with different MgO layer thicknesses (0 to 2.1 nm) grown by molecular beam epitaxy (MBE). The structural and magnetic properties of the CFS contact layers (20 nm thickness) were characterized by x-ray diffraction and superconducting-quantum-interference-device magnetometry. For the evaluation of the spin generation and transport, SV devices were processed and investigated by using a nonlocal SV arrangement. The SV measurements reveal an enhanced spin generation efficiency and an increased spin diffusion length in the GaAs transport channel with respect to CFS/GaAs reference structures. These results demonstrate the benefit of MgO interlayers for the performance of lateral SV structures with CFS contacts.