Application of a perpendicular magnetic field to charge neutral graphene is expected to result in a variety of broken symmetry phases, including antiferromagnetic, canted, and ferromagnetic. All these phases open a gap in bulk but have very different edge states and noncollinear spin order, recently confirmed experimentally. Here we provide an integrated description of both edge and bulk for th...

The quantum corrections to the energies of the point optical phonon modes Kohn anomalies in graphene nanoribbons NRs are investigated. We show theoretically that the longitudinal optical LO modes undergo a Kohn anomaly effect, while the transverse optical TO modes do not. In relation to Raman spectroscopy, we show that the longitudinal optical modes are not Raman active near the zigzag edge, wh...

The atomic structure of graphene edges is critical in determining the electrical, magnetic and chemical properties of truncated graphene structures, notably nanoribbons. Unfortunately, graphene edges are typically far from ideal and suffer from atomic-scale defects, structural distortion and unintended chemical functionalization, leading to unpredictable properties. Here we report that graphene...

Using in situ transmission electron microscopy, we observed the nucleation and growth of graphene bilayer edges (BLE) with ‘‘fractional nanotube’’-like structure from the reaction of graphene monolayer edges (MLEs). Most BLEs showed atomically sharp zigzag or armchair crystallographic facets in contrast to the atomically rough MLEs with irregular shapes, suggesting that the BLEs are much more s...

Graphene has unique electronic properties, and graphene nanoribbons are of particular interest because they exhibit a conduction bandgap that arises due to size confinement and edge effects. Theoretical studies have suggested that graphene nanoribbons could have interesting magneto-electronic properties, with a very large predicted magnetoresistance. Here, we report the experimental observation...

We study the transport properties of multiterminal graphene nanodevices using the Landauer-Buttiker approach and the tight binding model. We consider a four-terminal device made at the crossing of a zigzag and armchair nanoribbons and two types of T-junction devices. The transport properties of graphene multiterminal devices are highly sensitive to the details of the junction region. Thus the p...

Vibrations are often treated by very simple methods compared to electrons, but the precise atomic configuration becomes important for the stability of conductors when their size approaches nanometer scales. Graphene flakes are an example of a system, where atomically precise calculations are needed. Control of the edge topology of graphene nanostructures is critical to graphene-based electronic...