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Colossal enhancement of spin-orbit coupling in weakly hydrogenated graphene

TitleColossal enhancement of spin-orbit coupling in weakly hydrogenated graphene
Publication TypeJournal Article
Year of Publication2013
AuthorsBalakrishnan, Jayakumar, Koon GavinKokWai, Jaiswal Manu, Castro Neto A. H., and Özyilmaz Barbaros
JournalNature Physics
Volume9
Pagination284–287
Date Published05/2013
ISSN1745-2473
KeywordsCondensed-matter physics, Materials physics, nanotechnology
Abstract

Graphene’s extremely small intrinsic spin–orbit ({SO)} interaction makes the realization of many interesting phenomena such as topological/quantum spin Hall states and the spin Hall effect ({SHE)} practically impossible. Recently, it was predicted that the introduction of adatoms in graphene would enhance the {SO} interaction by the conversion of sp2 to sp3 bonds. However, introducing adatoms and yet keeping graphene metallic, that is, without creating electronic (Anderson) localization, is experimentally challenging. Here, we show that the controlled addition of small amounts of covalently bonded hydrogen atoms is sufficient to induce a colossal enhancement of the {SO} interaction by three orders of magnitude. This results in a {SHE} at zero external magnetic fields at room temperature, with non-local spin signals up to 100 Ω; orders of magnitude larger than in metals. The non-local {SHE} is, further, directly confirmed by Larmor spin-precession measurements. From this and the length dependence of the non-local signal we extract a spin relaxation length of {\textasciitilde}1 μm, a spin relaxation time of {\textasciitilde} 90 ps and a {SO} strength of 2.5 {meV.}

URLhttp://www.nature.com/nphys/journal/v9/n5/full/nphys2576.html
DOI10.1038/nphys2576

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