Dresden 2020 – wissenschaftliches Programm
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DS 29.2: Poster
Mittwoch, 18. März 2020, 15:00–18:00, P1A
Charge signals in non-local spin measurements and how to avoid them — Frank Volmer, •Anne Schmidt, Timo Bißwanger, Christoph Stampfer, and Bernd Beschoten — 2nd Institute of Physics and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
For spin-sensitive measurements a non-local device geometry is often used to avoid spurious signals due to the flow of charges. Nevertheless, in the vast majority of reported spin valve and Hanle measurements a background signal is observed which is not related to spins. This is especially true for lock-in based measurement techniques in which a charge signal, which is shifted in phase by 90∘ in regard to the spin signal, can show amplitudes several orders of magnitude higher than the actual spin signal. We discuss the origin of such charge signals and present a custom-made current source which is able to minimize their effects on spin measurements. By using this current source we are able to increase both the sensitivity and the speed in the measurement of graphene-based spin-valve devices with ferromagnetic Co electrodes and MgO tunnel barriers.