Eighty-Eight Percent Directional Guiding of Spin Currents with 90 mu m Relaxation Length in Bilayer Graphene Using Carrier Drift

Electrical control of spin signals and long distance spin transport are major requirements in the field of spin electronics. Here, we report the efficient guiding of spin currents at room temperature in high mobility hexagonal boron nitride encapsulated bilayer graphene using carrier drift. Our experiments, together with modeling, show that the spin relaxation length, that is 7.7 mu m at zero bias, can be tuned from 0.6 to 90 mu m when applying a DC current of -/+ 90 mu A, respectively. Our results also show that we are able to direct spin currents to either side of a spin injection contact. Eighty-eight percent of the injected spins flows to the left when I-dc = -90 mu A and eighty-two percent flows to the right when the drift current is reversed. These results show the potential of carrier drift for spin-based logic operations and devices.