Adsorbate-induced pinning of a charge-density wave in a quasi-1D metallic chains: Na on the In/Si(111)-(4x1) surface

Non-equilibrium lattice dynamics of one-dimensional In chains on Si(111) upon ultrafast optical excitation

The photoinduced structural dynamics of the atomic wire system on the Si(111)-In surface has been studied by ultrafast electron diffraction in reflection geometry. Upon intense fs-laser excitation, this system can be driven in around 1 ps from the insulating [Formula: see text] reconstructed low temperature phase to a metastable metallic [Formula: see text] reconstructed high temperature phase. Subsequent to the structural transition, the surface heats up on a 6 times slower timescale as determined from a transient Debye-Waller analysis of the diffraction spots. From a comparison with the structural response of the high temperature [Formula: see text] phase, we conclude that electron-phonon coupling is responsible for the slow energy transfer from the excited electron system to the lattice. The significant difference in timescales is evidence that the photoinduced structural transition is non-thermally driven.

Adatom-induced conductance modification of in nanowires: potential-well scattering and structural effects

First-principles calculations on the influence of adatoms (In, Pb, H, O) on the Landauer conductance of Si substrate-supported atomic-scale In nanowires are performed. Despite the increase of the total (and partially even local) density of states at the Fermi level due to the adsorption, all adatom species lower the nanowire conductance. Apart from hydrogen, which barely changes the transport properties, the conductance drop is pronounced, ranging from 17% for Pb to 38% for In. It is related to potential-well scattering and/or structural deformations of the nanowires.

Hydrogen-adsorption induced atomic rearrangement of a Pb monolayer on Si(111)

We have observed interesting H-atom adsorption induced atomic rearrangements of a Pb monolayer on the Si(111) with a scanning tunneling microscope. A hexagonal ringlike pattern is formed around the point defect. The interactions among nearby H-adsorbed defects can even produce interferencelike superstructures. Phase boundaries are found to either enhance or suppress the formation of the interference pattern. These phenomena are produced by an intricate interplay between electronic and atomic interactions as perturbed by the adsorbed hydrogen atoms.