Investigation of h-BN/Graphene Spin Valve*

Spintronics via two-dimensional materials offer promising applications in spin communications. Due to the extraordinary mobility and long diffusion length, graphene is still the subject of intense interest in spin transport. This study focuses on the investigation of the spin lifetime and diffusion length in graphene spin valve, including the extrapolation of the exponential decay of the spin signal with channel length and Hanle precession model. The graphene spin valve exhibits large non-local spin signal up to 40 Ω, with small switching field less than 200 Gauss. The extracted spin lifetime was between 100 and 200 ps, and the diffusion length was more than 4 μm. The spin-injection efficiency in graphene spin valve is further improved by controlling direct current as an injection source and using h-BN as a tunneling barrier.