Impurity-Mediated Early Condensation of a Charge Density Wave in an Atomic Wire Array

Abstract

We directly show how impurity atoms induce the condensation of a representative electronic phase, the charge density wave (CDW) phase, in atomic scale with scanning tunneling microscopy. Oxygen impurity atoms on the self-assembled metallic atomic wire array on a silicon crystal condense the CDW locally above the pristine transition temperature. More interestingly, the CDW along the wires is induced not by a single atomic impurity but by the cooperation of multiple impurities. First-principles calculations disclose the mechanism of the cooperation as the coherent superposition of the local lattice strain induced by impurities, stressing the coupled electronic and lattice degrees of freedom for the CDW. This opens the possibility of the strain engineering over electronic phases of atomic-scale systems.

Excited-state band mapping and momentum-resolved ultrafast population dynamics in In/Si(111) nanowires investigated with XUV-based time- and angle-resolved photoemission spectroscopy

“…In the case of In/Si(111) it is well known that the displacement of particular atoms can have significant effects on the band structure [31,33,34] which could be partially induced by strain. In addition, strain induced by oxygen defects has been shown to modify the CDW transition [59] while strain at step edges influences the transport of electrons [60]. However calculations assuming a strain value of 1 % along the atomic chain direction (compressive or tensile) produce changes to the m 1 band position of only 100 meV, which does not account for the effect we observe and tends to rule out strain as the dominant effect.…”

Tuning the conductivity along atomic chains by selective chemisorption

“…In case of Si(111)-In, e.g., the critical temperature T C for the metal insulator transition can be shifted to lower temperatures by adsorption of various atoms, which commonly destabilize the low-temperature phase. On the contrary, molecular oxygen atoms enhance cooperatively the interwire and intrawire coupling and lead to a stabilization of the insulating (8 × 2) configuration, which * tegenkamp@fkp.uni-hannover.de increases T C [12][13][14][15]. Moreover, on the Si(111)-Au (5 × 2) Si adatoms are intrinsically present and even mandatory for the formation of the geometry with the lowest (free) energy [16,17].…”

Si(775)-Au atomic chains: Geometry, optical properties, and spin order

“…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].…”