Edge structures for nanoscale graphene islands on Co(0001) surfaces.
Low-temperature scanning tunneling microscopy measurements and first-principles calculations are employed to characterize edge structures observed for graphene nanoislands grown on the Co(0001) surface. Images of these nanostructures reveal straight well-ordered edges with zigzag orientation, which are characterized by a distinct peak at low bias in tunneling spectra. Density functional theory based calculations are used to discriminate between candidate edge structures. Several zigzag-oriented edge structures have lower formation energy than armchair-oriented edges. Of these, the lowest formation energy configurations are a zigzag and a Klein edge structure, each with the final carbon atom over the hollow site in the Co(0001) surface. In the absence of hydrogen, the interaction with the Co(0001) substrate plays a key role in stabilizing these edge structures and determines their local conformation and electronic properties. The calculated electronic properties for the low-energy edge structures are consistent with the measured scanning tunneling images.
Nanoscience Institute, CNR , S3 Center, I-41125 Modena, Italy.
Deborah
D
Prezzi
Daejin
D
Eom
Kwang T
KT
Rim
Hui
H
Zhou
Shengxiong
S
Xiao
Colin
C
Nuckolls
Tony F
TF
Heinz
George W
GW
Flynn
Mark S
MS
Hybertsen