Magnetic linear and circular dichroism in core-level photoemission and magnetic circular x-ray dichroism in absorption for ultrathin films Fe/Pd(100).

Abstract

Magnetic circular x-ray dichroism (MCXD) experiments have been performed at the Fe ${\mathit{L}}_{2,3}$ absorption edges on ultrathin bct Fe layer epitaxially grown at room temperature on fcc Pd(100). In the magnetic circular and linear dichroism the asymmetry dependence in the Fe 2p and Fe 3p photoemission with the thickness of the Fe/Pd(100) film is compared to the simultaneously achieved absorption spectra in the MCXD. The magnetic circular x-ray dichroism results evidence a strong in-plane anisotropy along the [010] direction of the iron film, even for the ultrathin bct iron films grown at room temperature. In the thickness range of 2--3 equivalent monolayers, the magnetic orbital moment of iron is enhanced by a factor 5 [〈${\mathit{L}}_{\mathit{z}}$〉=(0.53\ifmmode\pm\else\textpm\fi{}0.02)${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$] compared to the bulk iron value, whereas the spin moment is meanly unaffected by the interface [2〈${\mathit{S}}_{\mathit{z}}$〉=(2.17\ifmmode\pm\else\textpm\fi{}0.15)${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$]. In core-level photoemission, both linear (Fe 3p) and circular (Fe 2p) magnetic dichroism show surprisingly very low asymmetries for 2-ML Fe/Pd(100). This seems to be in contradiction with the analysis of the magnetic dichroic signal at the ${\mathit{L}}_{2,3}$ Fe edges which leads for this film to a total magnetic moment about 2.70${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$. These measurements offer parameters related to the analysis of magnetic materials with magnetic circular and magnetic linear dichroism techniques. \textcopyright{} 1996 The American Physical Society.