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

Abstract

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 μm width and 5.6 μm 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 γ \textasciitilde 8.8 {\%} and λs \textasciitilde 2.2 μm at 2 K, respectively. The estimated spin relaxation rates were proportional to square of temperature, suggesting an Elliott-Yafet spin relaxation mechanism.