Anisotropic surface stress on W(110)

Anisotropic adsorbate-induced biaxial surface stress is measured for the adsorption of sub-monolayers of Fe and O on W(110). Half a monolayer of Fe induces compressive stress of − 2 N/m along W[001] and tensile stress of + 1 N/m along W[10], whereas a (2 × 1)-O structure induces compressive stress of − 1.1 N/m along W[10], and causes only a minute stress of − 0.1 N/m along W[001]. The O-induced surface stress is ascribed to a release of the anisotropic surface stress of the clean W crystal, whereas for Fe coverages, the surface stress of the Fe-W composite determines the measured stress.