Abstract
The geometry and electronic structure of self-assembled atomic scale Au wires on Si(775) are investigated within density functional theory. The calculated surface diagram indicates the existence of two stable configurations with Au coverages of 0.32 and 0.96 monolayers, respectively. The low-coverage structure is predicted to host an antiferromagnetic spin chain localized at the Si rest atom dangling bonds, while the high-coverage structure is characterized by a Au-induced $\ensuremath{\beta}\text{\ensuremath{-}}\sqrt{3}$-like structure on the terrace. These structural models are supported by the comparison of measured and calculated surface optical anisotropies.
Highlights
Self-assembled metallic nanowires on semiconductor surfaces are popular model systems to explore peculiarities of low-dimensional physics such as Peierls instabilities [1,2,3,4], Luttinger liquids [5], or solitons [6]
Compared to the Si(553)-Au surface, this is an increase of about 44% in terrace width, providing considerably more space for various surface reconstruction motifs, such as adatom/rest-atom rows, multiple Au chains, and Si honeycomb chains
We focused on the honeycomb configuration (H3-MTL) [25] and the conju√gate h√oneycomb-c√hained√trimer (CHCT) [26] model for α-( 3 × 3) and β-( 3 × 3), respectively [see Figs. 1√(e) and 1(f)]
Summary
Self-assembled metallic nanowires on semiconductor surfaces are popular model systems to explore peculiarities of low-dimensional physics such as Peierls instabilities [1,2,3,4], Luttinger liquids [5], or solitons [6]. Gold-induced wire structures on Si(553) and Si(557) are being discussed as possible hosts for spin chains [7,8]. We use density functional theory (DFT) to explore the geometry and possible spin polarization effects in Si(775)Au surfaces. The Au-induced atomic scale wires on Si(775) belong to the large group of quasi-one-dimensional structures obtained by Au deposition onto stepped silicon surfaces [10]. Compared to other Au-induced chain structures on Si surfaces Surface optical spectroscopy experiments and simulations are shown to support the predicted structural models. The electronic structure and spin order of the most stable geometries are explored in detail. Unlike other Si(hhk)-Au surfaces, which exhibit spin ordering at the step edge, Si(775)-Au is shown to host spin chains lying on the terraces
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