Direct observation of many-body charge density oscillations in a two-dimensional electron gas.
Quantum interference is a striking manifestation of one of the basic concepts of quantum mechanics: the particle-wave duality. A spectacular visualization of this effect is the standing wave pattern produced by elastic scattering of surface electrons around defects, which corresponds to a modulation of the electronic local density of states and can be imaged using a scanning tunnelling microscope. To date, quantum-interference measurements were mainly interpreted in terms of interfering electrons or holes of the underlying band-structure description. Here, by imaging energy-dependent standing-wave patterns at noble metal surfaces, we reveal, in addition to the conventional surface-state band, the existence of an 'anomalous' energy band with a well-defined dispersion. Its origin is explained by the presence of a satellite in the structure of the many-body spectral function, which is related to the acoustic surface plasmon. Visualizing the corresponding charge oscillations provides thus direct access to many-body interactions at the atomic scale.
Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Paolo
P
Sessi
Donostia International Physics Center (DIPC), Paseo de Manuel Lardizabal 4, 20018 San Sebastián/Donostia, Spain.|Departamento de Física de Materiales, Universidad del País Vasco, Apartado 1072, 20080 San Sebastián/Donostia, Spain.|IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.
Vyacheslav M
VM
Silkin
Donostia International Physics Center (DIPC), Paseo de Manuel Lardizabal 4, 20018 San Sebastián/Donostia, Spain.|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.|Tomsk State University, 634050 Tomsk, Russia.|Saint Petersburg State University, 198504 Saint Petersburg, Russia.
Ilya A
http://orcid.org/0000-0002-5598-222X
IA
Nechaev
Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Thomas
T
Bathon
Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Lydia
L
El-Kareh
Donostia International Physics Center (DIPC), Paseo de Manuel Lardizabal 4, 20018 San Sebastián/Donostia, Spain.|Departamento de Física de Materiales, Universidad del País Vasco, Apartado 1072, 20080 San Sebastián/Donostia, Spain.|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.|Tomsk State University, 634050 Tomsk, Russia.|Saint Petersburg State University, 198504 Saint Petersburg, Russia.
Evgueni V
EV
Chulkov
Donostia International Physics Center (DIPC), Paseo de Manuel Lardizabal 4, 20018 San Sebastián/Donostia, Spain.|Departamento de Física de Materiales, Universidad del País Vasco, Apartado 1072, 20080 San Sebastián/Donostia, Spain.|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.
Pedro M
PM
Echenique
Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.|Wilhelm Conrad Röntgen-Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Matthias
M
Bode