Spin pairing versus spin chains at Si(553)-Au surfaces

Abstract

Density-functional theory is used to probe the spin structure of the Si(553)-Au surface. A diamagnetic sp 2 + p rehybridized structure, where the dangling bonds are either filled with two spin-paired electrons or are empty, is more favorable and in better agreement with experiment than the generally accepted spin-chain model. The shallow potential energy surface of Si(553)-Au, together with the ordered array of empty dangling bonds, suggests this surface as susceptible for spin polarization by doping, however.

Organic Molecule Adsorption on Stepped Si–Au Surfaces: Role of Functional Group on Geometry and Electronic Structure

“…The dimerized double Au chain model of Krawiec is assumed for the Si(553)–Au substrate . If spin polarization is accounted for, a slightly more stable (1 × 3) periodicity is found at low temperature . However, this periodicity does not persist after adsorption at the step edge, and hence we work with the simpler (1 × 2) model.…”

“…For instance, the Si(553)–Au, Si(557)–Au, and Si(775)–Au surfaces with oriented steps lead to the formation of quasi‐one‐dimensional (1D) chains of metal atoms after partial Au coverage . Self‐assembly of the Au atoms acts to stabilize the 1D character of the surface geometry of the two‐dimensional (2D) object over long distances but also to generate interesting magnetic properties . The resulting stepped surfaces with metallic chains constitute possible templates for the interaction with organic molecules aiming at the formation of regular, ordered patterns of organic‐metal hybrid nanostructures .…”

Vibration-Driven Self-Doping of Dangling-Bond Wires on Si(553)-Au Surfaces

“…The Si step edge atoms feature dangling bonds (dbs). Two fully occupied sp 3 hybridized dbs alternate with one empty p orbital of sp 2 hybridized Si in the ground state (2,2,0) electron configuration [20]. This ×3 periodicity together with a ×2 periodicity due to Au chain dimerization is seen by scanning tunneling microscopy (STM) [17,[21][22][23] and low-energy electron diffraction (LEED) [24].…”

“…Collinear spin polarization is assumed. This methodology was recently shown to correctly describe the ground state of the 1 × 6 reconstructed Si(553)-Au surface [20]. A supercell containing six Si bilayers (H passivated at the bottom), a 450 eV plane-wave energy cutoff, and a 2 × 3 × 1 Brillouin-zone sampling ensure numerical convergence.…”

“…Such a charge redistribution characterizes the spin-liquid structure suggested by Erwin et al [14,24] for Si(553)-Au: It has a (2,2,1) electron configuration, i.e., two fully occupied dbs alternate with one singly occupied db along the step edge. The occupation of the formerly empty Si p orbital causes a sp 2 þ p → sp 3 rehybridization and moves the respective Si atom out of the planar sp 2 configuration [20].…”