Zigzag puts nanoribbons in a spin
CARBON
Recent advances in the experimental study of graphene -a single layer of hexagonally arranged carbon atoms -have prompted researchers from the University of California, Berkeley (UCB) to investigate graphene nanoribbons. Using a first-principles approach, Steven G. Louie and colleagues Young-Woo Son and Marvin L. Cohen have calculated that nanoribbons of graphene with zigzag edges can be made to carry a spin current [Son et al., Nature (2006) 444, 347]. The study demonstrates a novel mechanism for generating and manipulating carrier spins in a nanostructure using an applied electric field, and results suggest that the zigzag graphene nanoribbons (ZGNRs) could serve as the basis for nanosized spintronic devices. Graphene nanoribbons with a zigzag edge can be formed by cutting the graphene sheet through a uniform set of carbon-carbon bonds, forming homogeneous edges. This unique geometry permits the existence of peculiar, low-energy electronic states where all the spins are aligned either up or down along the edges. These ferromagnetic edge states interact antiferromagnetically (e.g. having the opposite