Spin Chains and Electron Transfer at Stepped Silicon Surfaces

Abstract

High-index surfaces of silicon with adsorbed gold can reconstruct to form highly ordered linear step arrays. These steps take the form of a narrow strip of graphitic silicon. In some cases - specifically, for Si(553)-Au and Si(557)-Au - a large fraction of the silicon atoms at the exposed edge of this strip are known to be spin-polarized and charge-ordered along the edge. The periodicity of this charge ordering is always commensurate with the structural periodicity along the step edge and hence leads to highly ordered arrays of local magnetic moments that can be regarded as "spin chains". Here, we demonstrate theoretically as well as experimentally that the closely related Si(775)-Au surface has - despite its very similar overall structure - zero spin polarization at its step edge. Using a combination of density-functional theory and scanning tunneling microscopy, we propose an electron-counting model that accounts for these differences. The model also predicts that unintentional defects and intentional dopants can create local spin moments at Si(hhk)-Au step edges. We analyze in detail one of these predictions and verify it experimentally. This finding opens the door to using techniques of surface chemistry and atom manipulation to create and control silicon spin chains.

arXiv comment7 pages, 4 figures; Supplement; accepted for publication in Nano Letters

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Cited by in corpus (3)

• Thermally-induced crossover from 2D to 1D behavior in an array of atomic wires: silicon dangling-bond solitons in Si(553)-Au
• Two-dimensional crossover and strong coupling of plasmon excitations in arrays of one-dimensional atomic wires
• Adsorbate induced manipulation of 1D atomic nanowires: Soliton mediated degradation of long-range order in the Si(553)-Au system