CVD bilayer graphene spin valves with 26 μm spin diffusion length at room temperature

We present inverted spin-valves fabricated from CVD-grown bilayer graphene (BLG) that show more than a doubling in device performance at room temperature compared to state-of-the art bilayer graphene spin-valves. This is made possible by a PDMS droplet-assisted full-dry transfer technique that compensates for previous process drawbacks in device fabrication. Gate-dependent Hanle measurements show spin lifetimes of up to 5.8 ns and a spin diffusion length of up to 26 $\mu$m at room temperature combined with a charge carrier mobility of $\approx$ 24 000 cm$^{2}$(Vs)$^{-1}$ for the best device. Our results demonstrate that CVD-grown BLG shows equally good room temperature spin transport properties as both CVD-graphene and even exfoliated single-layer graphene.