Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 19: Plasmonics and Nanooptics II

O 19.3: Talk

Monday, March 11, 2013, 16:30–16:45, H31

One-dimensional plasmons in arrays of monolayer silver wires on Si(557) — •Ulrich Krieg, Yu Zhang, Christian Brand, Herbert Pfnür, and Christoph Tegenkamp — Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstrasse 2, D-30167 Hannover, Germany

An array of metallic stripes of monatomic height and up to 10 atoms wide was prepared on the (111)-oriented mini-terraces of vicinal Si (557) via self assembly. By characterization with spot profile analysis LEED (SPA-LEED), STM and electron energy loss spectroscopy (EELS) with both high energy and momentum resolution, we demonstrate that a quasi one-dimensional system was prepared after adsorption between 0.5 and 1 ML of Ag. Only stripes that show √3×√3R30^∘ order turn out to be metallic with an almost linear dispersion of the plasmonic losses, in the direction parallel to the steps, while in perpendicular direction the plasmonic losses do not disperse at all. Therefore, the wires within the array seem to be electronically decoupled.

Due to the finite width, however, combined inter-subband-plasmon excitations become visible in the direction normal to the wires. The quantitative simulation is compatible with a wire width of 3.6 nm which agrees well with the width of the (111) terraces.

Interestingly, the electron concentration in the wires and thus the slope of the dispersion can be tuned in a wide range by doping these wires, making the Ag wires quite versatile for 1D conductance of plasmonic excitations.