Evidence for a Clean(2×2)R45°Surface Structure on Cr(100)

Abstract

Low-energy electron diffraction observations of carefully cleaned and annealed Cr(100) surfaces show a sharp and intense $(\sqrt{2}\times \sqrt{2})R45\mathrm{}°$ structure. Auger-electron spectroscopy measurements indicate that this "anomalous" structure is actually a clean-surface effect. A strong contamination-sensitive feature is revealed by angle-resolved photoemission and it is suggested that reconstruction results from an instability connected with a peak near $E_{\mathrm{F}}$ in the surface density of states of the Cr(100) (1×1) surface.