Gate dependent of nonlocal spin resistance in hydrogenated graphene

Graphene has been perceived as a promising spin channel material for spin field effect transistor and spin logic device because of long spin diffusion length arising from weak intrinsic spin-orbit interaction (SOI). Further, incorporation of SOI into graphene can lead to many interesting spin related phenomena; such as spin Hall effect, topological quantum spin Hall effect. The partial hydrogenation of the graphene has been suggested to induce local enhancement of SOI in graphene. The chemisorbed hydrogen can produce local magnetic moments and enhance SOI of graphene due to a change in orbital hybridization of the carbon network from sp2 into sp3. In this study, we introduce hydrogenated graphene by the dissociation of a hydrogen silsesquioxane (HSQ) resist. The ratio of hydrogenated carbon in graphene was determined to be 0.01~0.05 % for irradiation does of range 1~3 mC/cm2 which is determined by ID/IG ratio of Raman peak. We employed an H-bar type device to probe the nonlocal spin signal induced by spin Hall and inverse spin Hall effect. The geometry of the studied H-bar devices fabricated by E-beam lithography has channels of 1 mm width and 2, 3, 4 mm length. Detailed study or non-local spin signal in hydrogenated graphene will be discussed further

Gate dependent non-local spin resistance in an Au-patched graphene

Enhanced spin-orbit coupling in grapheme can induce spin Hall effect, which can be adapted to electrically generate or detect a spin current in the spin logic device without a ferromagnet. Recently, spin Hall effect in decorated graphenes has been experimentally observed by non-local transport studies. However, results on the non-local measurements in graphene hall bar devices exploiting spin Hall effect have been under controversy. In this study, we introduced an ultra-thin Au-patch on a graphene surface to enhance the spin-orbit coupling, and employed an H-bar type device to probe the nonlocal spin signal induced by spin Hall effect. The geometry of the studied H-bar devices has channels of 1 ??m width and 5.6 ??m length. An ultra-thin Au patch (\textasciitilde 1 nm) was deposited by a thermal evaporation. And in-plane field dependent spin precession signature can be observed at particular gate voltage. At that point, the spin hall angle and the spin relaxation length of the Au-patch graphene device were ?? \textasciitilde 8.8 {\%} and ??s \textasciitilde 2.2 ??m at 2 K, respectively. The estimated spin relaxation rates were proportional to square of temperature, suggesting an Elliott-Yafet spin relaxation mechanism