Symmetry-dependent screening of surface plasmons in ultrathin supported films: The case of Al/Si(111)
Artikel i vetenskaplig tidskrift, 2011

A joint theoretical and experimental study of plasmon excitations for Al overlayers on Si(111) has been carried out. The presence of the substrate is found to drastically modify the hybridization and charge density response of the surface plasmons of the metal overlayers. The symmetric mode, which is polarized toward the Al/Si interface, is strongly damped in intensity and significantly redshifted in energy. However, the antisymmetric mode, which is polarized to the metal-vacuum interface, is essentially unaffected by the presence of the substrate. A low-energy acoustic plasmon mode is also found in a one monolayer Al film and is almost unaffected by the substrate. The calculated plasmon dispersions with substrate are in good agreement with experimental data measured by electron energy loss spectroscopy. Our results suggest that interaction and screening at the subnanometer scale are symmetry dependent, a conclusion that may have general implications in other thin films and related structures.

energy

phase

electronic

excitations

layers

alkali-metal overlayers

thin-films

dispersion

scattering

substrate

density-response function

Författare

Zhe Yuan

Chalmers, Teknisk fysik, Material- och ytteori

Y. Jiang

Y. Gao

Mikael Käll

Chalmers, Teknisk fysik, Bionanofotonik

Shiwu Gao

Göteborgs universitet

Physical Review B - Condensed Matter and Materials Physics

1098-0121 (ISSN)

Vol. 83

Ämneskategorier

Fysik

Den kondenserade materiens fysik

DOI

10.1103/PhysRevB.83.165452