Regensburg 2019 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: Magnetism Poster A

MA 15.34: Poster

Dienstag, 2. April 2019, 10:00–13:00, Poster E

Photoinduced modulation of resistivity in metallic wires under DC Bias — Lea Apel, Şaban Tirpanci, •Palvan Seyidov, and Georg Woltersdorf — Institutte of Physics, Martin-Luther-Universität Halle-Wittenberg

Charge to spin current conversion due to the spin Hall effect (SHE) was intensely studied in the last decade. Even in metallic wires 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 wire edges using a novel light helicity-dependent scanning photovoltage measurement technique at room temperature [2]. Unfortunately a reasonable physical explanation of 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 similiar 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 observed 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. Phyy. Rev. Lett. 119,087207(2017)

[2]L. Yang et al., Nat. Commun. 9,2492(2018)