title: Charge density waves in the graphene sheets of the superconductor CaC(6).
abstract: Graphitic systems have an electronic structure that can be readily manipulated through electrostatic or chemical doping, resulting in a rich variety of electronic ground states. Here we report the first observation and characterization of electronic stripes in the highly electron-doped graphitic superconductor, CaC(6), by scanning tunnelling microscopy and spectroscopy. The stripes correspond to a charge density wave with a period three times that of the Ca superlattice. Although the positions of the Ca intercalants are modulated, no displacements of the carbon lattice are detected, indicating that the graphene sheets host the ideal charge density wave. This provides an exceptionally simple material-graphene-as a starting point for understanding the relation between stripes and superconductivity. Furthermore, our experiments suggest a strategy to search for superconductivity in graphene, namely in the vicinity of striped 'Wigner crystal' phases, where some of the electrons crystallize to form a superlattice.
authors: London Centre for Nanotechnology, UCL, London WC1H 0AH, UK. kaveh.r@gmail.com
authors: K C
authors: KC
authors: Rahnejat
authors: C A
authors: CA
authors: Howard
authors: N E
authors: NE
authors: Shuttleworth
authors: S R
authors: SR
authors: Schofield
authors: K
authors: K
authors: Iwaya
authors: C F
authors: CF
authors: Hirjibehedin
authors: Ch
authors: Ch
authors: Renner
authors: G
authors: G
authors: Aeppli
authors: M
authors: M
authors: Ellerby
mesh_terms: D002244:Carbon / Q000737:chemistry*; D004553:Electric Conductivity; D006108:Graphite / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling; D049329:Nanostructures / Q000737:chemistry; D036103:Nanotechnology
chemical_list: D002244:Carbon; D006108:Graphite