Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 29: Metallic nanowires on semiconductor surfaces

O 29.8: Talk

Tuesday, March 13, 2018, 12:15–12:30, MA 144

Control of plasmonic excitations in atomic arrays by adsorbates — •Zamin Mamiyev, Timo Lichtenstein, Christoph Tegenkamp, and Herbert Pfnür — Institut für Festkörperphysik, Leibniz Universität Hannover, Hannover, Germany

Self-assembled atomic wires on vicinal Si surfaces serve the possibility to investigate fundamental properties of low-dimensional metallic systems. Electronic properties of such ultimate wires are strongly correlated with local structural motifs such as atomic arrangements, terrace width as well as inter- and intrawire distances. Therefore, the electronic correlation on such metallic wires is possible without direct contact with the atomic chains by the proximity effects. In this work modification of plasmonic excitations on Au-Si(hhk) surfaces by O₂ and H₂ adsorption has been studied via EELS-LEED with high resolution in energy and momentum. While the plasmon energy decreases by atomic hydrogen on Au-Si(553), gap opening is observed on Au-Si(557). Theoretical results show that hydrogen adsorption on Si step edges transfers charges to the metallic chains and increases band filling of Au-induced bands on Si(553), resulting in a metal-insulator transition. However, oxygen affects plasmon dispersion only on Au-Si(557), probably due to its higher chemical reactivity. Oxygen adsorption on Au-Si(557) is consistent with calculations that show that oxidation of adatom rows decreases the plasmon frequency. On the other hand, the excess amount of adsorbates induces disorder and finite propagation lengths.