Unoccupied surface states of Cr(001) detected by K-resolved inverse photoemission

Abstract

The energies of unoccupied surface states of Cr(001) have been measured using angle-resolved inverse photoemission spectroscopy. Spectra of the clean surface were recorded varying the momentum parallel to the surface along the \\ ̄ gG- \\ ̄ gD-X̄ and \\ ̄ gG- \\ ̄ gS-M̄ high-symmetry directions. The surface states were distinguished from the bulk d bands by contaminating the surface and comparing the difference between the clean and contaminated spectra. This showed surface states near E F and 1.7 eV above it. In the spectra of the clean surface, the surface states could be distinguished from the bulk d bands at some angles of incidence and appeared to disperse very little. The observed surface states are identified with the unoccupied majority and minority spin surface states calculated by Klebanoff et al. [1]. The energies of the bulk bands were in agreement with the ASA-LMTO calculation of Skriver [2].