title: Magnetism and perfect spin filtering effect in graphene nanoflakes.
abstract: Magnetic and spin-polarized transport properties in zigzag-edged graphene nanoflakes were investigated from first-principles calculations. Ferrimagnetic structure was found to be the ground state for triangular shaped graphene flakes. Magnetism is weakened by doping B or N atoms into the flakes, and it is enhanced if F atoms are doped in certain sublattices of the flakes. The magnetic properties can be rationalized by the behaviors of dopants as well as interactions between dopants and the host atoms. A perfect (100%) spin filtering effect was achieved for the pure or B doped graphene flake sandwiched between two gold electrodes. The orientation of the spin current is found to be flipped if the flake is doped with N, O, or F atoms. The orientation-tunable spin filtering effect is potentially useful in practical applications.
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai, People's Republic of China.
authors.forename: W
authors.initials: W
authors.lastname: Sheng
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Ning
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Guo