  We study spin dependent transport through a magnetic bilayer graphene
nanojunction configured as two dimensional normal/ferromagnetic/normal
structure where the gate-voltage is applied on the layers of ferromagnetic
graphene. Based on the fourband Hamiltonian, conductance is calculated by using
Landauer Butikker formula at zero temperature. For parallel configuration of
the ferromagnetic layers of bilayer graphene, the energy band structure is
metallic and spin polarization reaches to its maximum value close to the
resonant states, while for antiparallel configuration, the nanojunction behaves
as a semiconductor and there is no spin filtering. As a result, a huge
magnetoresistance is achievable by altering the configurations of ferromagnetic
graphene especially around the band gap.
