Bias-dependent D'yakonov-Perel' spin relaxation in bilayer graphene

We calculate the spin relaxation time of mobile electrons due to spin precession between random impurity scattering (D'yakonov-Perel' mechanism) in electrically gated bilayer graphene analytically and numerically. Due to the trigonal warping of the bandstructure, the spin relaxation time exhibits an interesting non-monotonic behavior as a function of both the Fermi energy and the interlayer bias potential. Our results are in good agreement with recent four-probe measurements of the spin relaxation time in bilayer graphene and indicate the possibility of an electrically-switched spin device.