Magnetic properties of Fe films on flat and vicinal Au(111): Consequences of different growth behavior

Abstract

The epitaxial growth of Fe on flat Au(111) differs from Fe on vicinal Au(111). One consequence is a different critical Fe overlayer thickness at which a structural phase transition from fcc(111) to bcc(110) takes place. The critical thickness is higher for Fe on vicinal Au(111) than on flat Au(111). Accompanied with the structural phase transition is a spin-reorientation transition of the easy-magnetization direction from out of plane to in plane. In agreement with the impeded phase transition we observe an impeded spin-reorientation transition on vicinal Au(111). The spin-reorientation transition, however, proceeds in a narrow coverage range while the structural phase transition occurs gradually over a larger thickness range. A further consequence of the different growth behavior is a different topography for thicknesses beyond the phase transition. Fe on flat Au(111) exhibits a sixfold symmetry, Fe on vicinal Au(111) only a twofold symmetry. The different symmetries influence the magnetic properties: while for bcc Fe(110) on flat Au(111) no easy-magnetization direction could be determined, we identified a preferred direction for Fe on vicinal Au(111) which is perpendicular to the step edges. The twofold symmetry causes an uniaxial magnetic behavior. This knowledge of the magnetization behavior is essential for correctly analyzing spin-resolved measurements of the electronic structure as demonstrated by photoemission measurements.