Temperature dependence of surface stress across an order-disorder transition: p(1x2)O/W(110)

TL;DR

This study investigates how surface stress in a p(1x2) oxygen layer on W(110) varies with temperature across an order-disorder transition, combining experimental strain measurements with ab initio calculations.

Contribution

It provides quantitative analysis of temperature-dependent surface stress changes using low-energy electron diffraction and first-principles calculations across the transition.

Findings

Surface stress decreases from -1.1 to -0.2 N/m along [1-10]

Surface stress decreases from 5.1 to 3.4 N/m along [001]

Strain relaxation occurs at domain boundaries, scaling inversely with domain size

Abstract

Strain relaxations of a p(1x2) ordered oxygen layer on W(110) are measured as a function of temperature across the disordering transition using low-energy electron diffraction. The measured strains approach values of 0.027 in the [1-10] and -0.053 in the [001] direction. On the basis of the measured strain relaxations, we give quantitative information on temperature-dependent surface stress using the results of ab initio calculations. From the surface formation energy for different strains, determined by first-principles calculations, we estimate that surface stress changes from -1.1 for the ordered phase to -0.2N/m for the disordered one along [1-10], and from 5.1 to 3.4 N/m along [001]. Moreover, our observation that the strains scale inversely with domain size confirms that the strain relaxation takes place at the domain boundaries.