▎ 摘　　要

We investigate the spin-dependent transport properties of graphene nanostructures modulated by effective exchange field and Fermi velocity. The Brewster-like angle of spin transport becomes large and the spin-precession length becomes short with a decrease of the Fermi velocity in effective exchange field region. As a consequence, the magnetoresistance is enhanced remarkably and the number of the magnetoresistance dips increases. In the graphene-based periodic velocity barrier with the modulations of the electrostatic potential and the effective exchange field, the maximum of the magnetoresistance dips is a number of times larger than that of zero electrostatic potential. (C) 2013 AIP Publishing LLC.