Determination of the lattice relaxation at the Yb(111) surface using chemical-shift photoelectron diffraction

Abstract

A quantitative analysis of the surface relaxation of thick Yb(111) single-crystal films grown on W(110) has been performed by photoelectron diffraction technique using high-energy resolution photoemission spectra of the surface core-level shift of Yb $4f.$ Our results demonstrate that Yb grows epitaxially in a fcc structure without surface reconstruction. The surface atoms present an inward relaxation of the first and second layers by $(3.6\ifmmode\pm\else\textpm\fi{}0.3)%$ and $(1.9\ifmmode\pm\else\textpm\fi{}0.2)%$ of the bulk interlayer spacing, respectively. The appearance of the d-like surface-state at Yb(111) is assumed to be responsible for the inward surface relaxation.