Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 115: Metallic Nanowires on the Atomic Scale (jointly with DS, O)
TT 115.11: Talk
Friday, March 20, 2015, 12:30–12:45, H 2032
Plasmonic excitations in Au/Si(553) and Au/Si(775) — •Timo Lichtenstein1, Julian Aulbach2, Jörg Schäfer2, Christoph Tegenkamp1, and Herbert Pfnür1 — 1Leibniz Universität Hannover, Institut für Festkörperphysik, 30167 Hannover, Germany — 2Physikalisches Institut and Röntgen Center for Complex Materials Systems (RCCM), Universität Würzburg, 97074 Würzburg, Germany
Si(553) and Si(775) surfaces are highly stabilized by Au adsorption resulting in chain reconstructions of Au and Si atoms. For low temperatures the chains develop a change in periodicity not because of a Peierl’s transition but because of frozen spin-polarization. Therefore, they remain metallic at low temperature. Here we study the metallicity of these systems by investigating the plasmons of the spin-split bands.
The sample quality was controlled with SPA-LEED. The plasmon dispersion was then investigated via a combination of EELS and SPA-LEED setup providing both high energy and momentum resolution. Measurements were carried out at room temperature and at 77 K.
Similar to Au/Si(557) [1], the dispersion for Au/Si(553) and Au/Si(775) is also linear for k|| > 0.07 Å−1, a typical signature in 1D. Compared to Au/Si(557) the slope is decreased by a factor of about 2, reflecting the lower electron density of 1×107 cm−1. For lower k|| the dispersion relations saturate at 200 meV (150 meV) for Au/Si(553) (Au/Si(775)), indicative of quantum well states perpendicular to the steps expected for electronically well separated wires [2].
[1] T. Nagao et al., Phys. Rev. Lett. 97(11), 116802 (2006).
[2] U. Krieg et al., J. Phys.: Condens. Matter 25(1), 14013 (2013)