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arXiv · 1607.04647

Tunable spin-orbit coupling and symmetry-protected edge states in graphene/WS$_2$

Bowen Yang·Min-Feng Tu·Jeongwoo Kim·Yong Wu·Hui Wang·Jason Alicea·Ruqian Wu·Marc Bockrath·Jing Shi
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Abstract

We demonstrate clear weak anti-localization (WAL) effect arising from induced Rashba spin-orbit coupling (SOC) in WS$_2$-covered single-layer and bilayer graphene devices. Contrary to the uncovered region of a shared single-layer graphene flake, WAL in WS$_2$-covered graphene occurs over a wide range of carrier densities on both electron and hole sides. At high carrier densities, we estimate the Rashba SOC relaxation rate to be $\sim 0.2 \rm{ps}^{-1}$ and show that it can be tuned by transverse electric fields. In addition to the Rashba SOC, we also predict the existence of a `valley-Zeeman' SOC from first-principles calculations. The interplay between these two SOC's can open a non-topological but interesting gap in graphene; in particular, zigzag boundaries host four sub-gap edge states protected by time-reversal and crystalline symmetries. The graphene/WS$_2$ system provides a possible platform for these novel edge states.

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Bowen Yang, Min-Feng Tu, Jeongwoo Kim, Yong Wu, Hui Wang, Jason Alicea, Ruqian Wu, Marc Bockrath, Jing Shi. 2016-07-15. Tunable spin-orbit coupling and symmetry-protected edge states in graphene/WS$_2$. https://doi.org/10.1088/2053-1583%2F3%2F3%2F031012

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