Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Graphene: Electronic properties, structure and substrate interaction II (joint session O/TT)

O 27.8: Vortrag

Dienstag, 13. März 2018, 12:30–12:45, MA 043

Strong spin-orbit interaction in graphene/WSe₂ probed at local scale — •Mikhail Fonin¹, Felix Förschner¹, Fabian Paschke¹, Lena Stoppel¹, Julia Tesch¹, Yuriy Dedkov^2,1, and Andor Kormányos¹ — ¹Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany — ²Department of Physics, Shanghai University, 200444 Shanghai, China

Deposition on transition metal dechalcogenide substrates allow to considerably modify the strength of spin-orbit interaction (SOI) in graphene, as shown in recent magnetotransport experiments [1,2]. Here we investigate structure and electronic properties of graphene on tungsten diselenide (WSe₂) by means of scanning tunneling microscopy and spectroscopy. In external magnetic field local spectroscopic measurements reveal pronounced Landau level sequences on graphene/WSe₂. Detailed analysis of the obtained tunneling spectra shows that each Landau level is split into subpeaks, where the splitting strength grows with increasing magnetic fields. We attribute the splittings to the manifestation of substrate induced SOI in graphene. A comparison of the experimental splitting strengths with the those yielded by a spin-dependent low-energy effective Hamiltonian allows the determination of the SOI coupling constants for the Rashba term and the so-called spin-valley coupling term. Furthermore, we map the real space fluctuations of the SOI coupling strength which correlate with the variations of local electronic potential.

[1] Z. Wang et al., Nature Comm. 6, 8339 (2015). [2] Z. Wang et al. Phys. Rev. X 6, 041020 (2016).