Spin-dependent conductance and shot noise in graphene based periodic velocity barrier.

We theoretically investigate the spin-dependent conductance and shot noise properties in graphene based periodic velocity barrier structure under Rashba spin–orbit interaction (RSOI). The system consists of graphene sheet in which the Fermi velocity and the electrostatic potential vary in space. We find that the spin-dependent conductance and shot noise in graphene can be efficiently controlled by tuning the Fermi velocity. Moreover, changing the Fermi velocity allows us to change the positions of the Dirac points. The spin-dependent Fano factor without and with spin flip increases and decreases, respectively with increasing the RSOI strength. When Fermi velocity in the barriers is smaller than the velocity outside the barriers, we find that the Fano factor for outgoing electrons with opposite spins has an oscillatory behavior with respect to the RSOI strength. Specifically, as the number of velocity barriers increases or Fermi velocity decreases the spin polarization increases. [ABSTRACT FROM AUTHOR]