Comparative study of adatom manipulation on several fcc metal surfaces

TL;DR

This study compares adatom manipulation energy barriers across various fcc metal surfaces, revealing how tip/substrate composition influences lateral and vertical manipulation processes, with implications for nanoscale surface engineering.

Contribution

It provides a systematic analysis of adatom manipulation barriers on different fcc metal surfaces, including heterogeneous systems, using total energy calculations with many-body potentials.

Findings

Manipulation barriers vary significantly among metals.

Ag(111) shows the lowest lateral barrier among homogeneous systems.

Heterogeneous Cu/Pt systems exhibit asymmetric manipulation ease.

Abstract

For a set of fcc metals our total energy calculations, based on many body potentials, show that activation barriers for lateral manipulation of an adatom at a step edge depend on the tip/substrate composition. Of the six homogeneous systems studied, manipulation on stepped Ag(111) showed the lowest energy barrier for adatom hopping towards the tip, although the relative probability for this process was largest on Cu(111). For a representative Cu/Pt heterogeneous system we find lateral manipulation of a Pt adatom along a step on Pt(111) by a Cu(100) tip to be energetically much less favourable than the reverse case of a Cu adatom manipulated by a Pt(100) tip. In the case of vertical manipulation, atomic relaxations of the tip and its neighbouring atoms are found to be prominent and tip induced changes in the bonding of the adatom to its low coordinated surroundings help explain the relative ease with which an adatom next to a step edge or a kink site, may be pulled, as compared to that on a flat surface.