N.B. Brookes

Potassium adsorption and an unoccupied surface state on Fe(001)

Spin-polarized photoemission studies of potassium adsorption on an Fe(001) surface provide evidence of a minority-spin surface state sitting immediately above the Fermi level on the clean surface. This state of symmetry is associated with the surface state predicted in first-principles calculations and the state utilized in chemically selective scanning tunnelling microscopy studies of the Fe(001) surface.

Spin-polarized core-level photoemission of oxidized Fe(001)(invited)

The combination of spin‐polarization detection with core‐level photoemission to give spin‐polarized electron spectroscopy for chemical analysis provides new information on the oxidation of an iron surface. During the initial stage of oxidation the predominant phase is of a ferrimagnetic γ‐Fe2O3 form. The observed antiferromagnetic coupling of this oxide with the iron substrate is attributed to the superexchange interaction mediated by an oxygen ion. This provides evidence for a site exchange mechanism during the initial oxidation. Annealing transforms this oxide into an antiferromagnetic FexO form which is also present at the initial stage.