Strain effect on spin polarization in a graphene junction

We investigate the strain effect on the spin-dependent transport in a graphene junction with spin-orbit coupling and a gate voltage. We find that uniaxial strain along the armchair direction breaks the transmission probability symmetry with respect to the incident angle, reduces the spin-flipped transmission probability, and extends the transmission gap as regard to the Fermi energy, while strain along the zig-zag direction has very little effect on transmission probabilities. We analyze the spin polarization as a function of the strain magnitude, direction, voltage, and area width. Selecting the proper strain direction and magnitude for both the Klein tunneling and classical cases, the direction of the spin-polarization vector can be controlled and its magnitude is dramatically enhanced. Strain will expand the non-zero range of the magnitude of the spin-polarization vector with respect to voltage. Increasing the strain area width over a threshold, keeps the magnitude of the spin-polarization vector stable.