Charge to spin current conversion due to the spin Hall effect (SHE) was intensely studied in the last decade. For metallic wires even direct magneto-optic detection of the current-induced spin accumulation has been reported [1]. Recently, Yang et al. demonstrated the direct visualization of current-induced spin accumulation at the wire edges using a novel light helicity-dependent scanning photovoltage measurement technique in metallic wires at room temperature [2]. Unfortunately, a resonable physical explanation of the observed signals was not presented. In our experiments we reproduce the results by Yang et al. qualitatively for Pt wires with a spatial resolution of 300 nm, using a very similar setup as discussed in [2]. We compare the spatial dependence of the photovoltages in Pt, Ta and Cu wire structures under DC bias. In Pt we find signals at the wire edges, which have a similar magnitude and the same symmetry as in [2] upon switching the current direction. However, we also observe very similar helicity dependent photo voltage signals also for Cu and Ta wires under DC bias. Therefore, we conclude that most of the signals we observe at the wire edges are not caused by the SHE induced spin accumulation. We perform a careful analysis of the possible origins of these signals. [1] C. Stamm et al. Phys. Rev. Lett. (2017) [2] L. Yang et al., Nat. Commun. 9, 2492 (2018)

Date Published: 10 September 2019
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Proc. SPIE 11090, Spintronics XII, 1109030 (10 September 2019); doi: 10.1117/12.2529946

Published in SPIE Proceedings Vol. 11090:
Spintronics XII
Henri-Jean M. Drouhin; Jean-Eric Wegrowe; Manijeh Razeghi, Editor(s)