Spin transport in ferromagnetic bilayer graphene superlattice

Using the transfer-matrix method, Spin transport in ferromagnetic bilayer graphene superlattice, which can be rea- lized by putting a series of ferromagnetic insulator layers on top of a bilayer grapheme is studied. The ferromagnetic layers with exchange energy ??? are in contact with gate of potential energy ??. It is considered that the magnetiza- tion in the two ferromagnetic layers are aligned parallel (P) and antiparallel (AP) to each other. The spin transmis- sions probability (?? and ??) and the spin conductance (?? and ??) are studied. The spin polarization is calculated through the spin conductance. The total conductance (?? ? and ?? ?? ) is also considered. It is found that perfect reflec- tion can occur at normal incident, i.e., ?? ???0. The spin conductance and the swpin polarization are found to exhibit oscillatory depending on the barrier height. The highest value of oscillating amplitude for SP% can rich 100% or (-100%) under special condition.