title: Correlated motion of electrons on the Au(111) surface: anomalous acoustic surface-plasmon dispersion and single-particle excitations.
abstract: The linear dispersion of the low-dimensional acoustic surface plasmon (ASP) opens perspectives in energy conversion, transport, and confinement far below optical frequencies. Although the ASP exists in a wide class of materials, ranging from metal surfaces and ultrathin films to graphene and topological insulators, its properties are still largely unexplored. Taking Au(111) as a model system, our combined experimental and theoretical study revealed an intriguing interplay between collective and single particle excitations, causing the ASP associated with the Shockley surface state to be embedded within the intraband transitions without losing its sharp character and linear dispersion.
authors.affiliation: Dipartimento di Fisica dell'Universitá di Genova and IMEM-CNR Unitá Operativa di Genova, Via Dodecaneso 33, 15146 Genova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Vattuone
authors.affiliation: Dipartimento di Fisica dell'Universitá di Genova and IMEM-CNR Unitá Operativa di Genova, Via Dodecaneso 33, 15146 Genova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Smerieri
authors.affiliation: Institut für Festkörperphysik, Abteilung Atomare und Molekulare Strukturen, Leibniz Universität Hannover, Appelstraße 2, D-30167 Hannover, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Langer
authors.affiliation: Institut für Festkörperphysik, Abteilung Atomare und Molekulare Strukturen, Leibniz Universität Hannover, Appelstraße 2, D-30167 Hannover, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Tegenkamp
authors.affiliation: Institut für Festkörperphysik, Abteilung Atomare und Molekulare Strukturen, Leibniz Universität Hannover, Appelstraße 2, D-30167 Hannover, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Pfnür
authors.affiliation: Departamento de Física de Materiales, Facultad de Ciencias Químicas, Universidad del País Vasco, Apartado 1072, 20080 San Sebastián/Donostia, Spain and Donostia International Physics Center (DIPC), Paseo de Manuel Lardizabal 4, 20018 San Sebastián/Donostia, Spain and IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.
authors.forename: V M
authors.initials: VM
authors.lastname: Silkin
authors.affiliation: Departamento de Física de Materiales, Facultad de Ciencias Químicas, Universidad del País Vasco, Apartado 1072, 20080 San Sebastián/Donostia, Spain and Donostia International Physics Center (DIPC), Paseo de Manuel Lardizabal 4, 20018 San Sebastián/Donostia, Spain and Centro de Física de Materiales CFM-Materials Physics Center MPC, Centro Mixto CSIC-UPV/EHU, Paseo de Manuel Lardizabal 5, 20018 San Sebastián/Donostia, Spain.
authors.forename: E V
authors.initials: EV
authors.lastname: Chulkov
authors.affiliation: Departamento de Física de Materiales, Facultad de Ciencias Químicas, Universidad del País Vasco, Apartado 1072, 20080 San Sebastián/Donostia, Spain and Donostia International Physics Center (DIPC), Paseo de Manuel Lardizabal 4, 20018 San Sebastián/Donostia, Spain and Centro de Física de Materiales CFM-Materials Physics Center MPC, Centro Mixto CSIC-UPV/EHU, Paseo de Manuel Lardizabal 5, 20018 San Sebastián/Donostia, Spain.
authors.forename: P M
authors.initials: PM
authors.lastname: Echenique
authors.affiliation: Dipartimento di Fisica dell'Universitá di Genova and IMEM-CNR Unitá Operativa di Genova, Via Dodecaneso 33, 15146 Genova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Rocca