title: Fermi gap stabilization of an incommensurate two-dimensional superstructure.
abstract: The compressed, incommensurate approximately (9.5 x 9.5) moire superstructure of the Ag monolayer on Cu(111) displays a filled surface state band with a Fermi energy gap at the Brillouin zone boundary. By contrast, the surface band is gapless for the less compressed, commensurate (9 x 9) moire of two Ag layers. A simple estimate of the energy gain rendered by opening this gap gives a value similar to the elastic energy change required to modify the commensurate structure, thereby suggesting that the approximately (9.5 x 9.5) incommensurate phase is stabilized by such a gap opening. The possible presence of a charge density wave state is discussed.
authors.affiliation: Donostia International Physics Center, Paseo Manuel Lardizabal 4, E-20018 Donostia-San Sebastián, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Schiller
authors.forename: J
authors.initials: J
authors.lastname: Cordón
authors.forename: D
authors.initials: D
authors.lastname: Vyalikh
authors.forename: A
authors.initials: A
authors.lastname: Rubio
authors.forename: J E
authors.initials: JE
authors.lastname: Ortega