  We report the discovery of a strong and tunable spin lifetime anisotropy with
excellent spin lifetimes up to 7.8 ns in dual-gated bilayer graphene.
Remarkably, this realizes the manipulation of spins in graphene by
electrically-controlled spin-orbit fields, which is unexpected due to
graphene's weak intrinsic spin-orbit coupling. We utilize both the in-plane
magnetic field Hanle precession and oblique Hanle precession measurements to
directly compare the lifetimes of out-of-plane vs. in-plane spins. We find that
near the charge neutrality point, the application of a perpendicular electric
field opens a band gap and generates an out-of-plane spin-orbit field that
stabilizes out-of-plane spins against spin relaxation, leading to a large spin
lifetime anisotropy. This intriguing behavior occurs because of the unique
spin-valley coupled band structure of bilayer graphene. Our results demonstrate
the potential for highly tunable spintronic devices based on dual-gated 2D
materials.
