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Chemisorbed {ital p}(1{times}1) oxygen on ultrathin epitaxial Fe films grown on W(001) are studied using spin- and angle-resolved photoemission. In agreement with theoretical predictions, single-monolayer (ML) Fe films on W(001) are found to be nonmagnetic; 2-ML-thick Fe films are magnetic, and chemisorbed {ital p}(1{times}1) oxygen does not destroy the magnetism. Even- and odd-symmetry oxygen 2{ital p}-derived bands are measured along the {bar {Gamma}}-{ital {bar X}} and {bar {Gamma}}-{ital {bar M}} directions of the two-dimensional Brillouin zone. Oxygen-derived features in the photoemission spectra exhibit magnetic exchange splitting as well as spin-dependent intrinsic linewidths that are governed by lifetime effects and initial-state mixing with Fe bands. Oxygen 2{ital p}-band narrowing resulting from the expanded Fe thin-film lattice constant is observed. The results are compared with relevant calculations and corresponding experimental studies of {ital p}(1{times}1) oxygen on bulk Fe(001) surfaces.

Mesure de la variation avec la temperature, des courbes des distributions des energies des bandes de valence des films ultraminces de Fe/W(100), a l'aide de la photoemission a angle et a spin resolus. Les structures majoritaires et minoritaires au point Γ sont stationnaires lorsque l'on eleve la temperature; un elargissement apparent des pics est cause par l'emergence de pics «extraordinaires». La comparaison avec un calcul du cluster (amas) suggere que de l'ordre ferromagnetique a courte distance existe au-dessus de Tc dans le film d'epaisseur egale a 1,5 monocouche

Spin-polarized electron-energy-loss spectra have been obtained from Cu(100) and Mo(110) surfaces by use of a polarized primary beam coupled with energy-resolved spin analysis of the scattered electrons. The data reveal strong evidence for inelastic spin-exchange scattering. In particular, a prominent polarization-loss feature evident in the Mo(110) data correlates with the joint density of states available for electron-hole pair excitation. Exchange scattering is observed to decrease rapidly with increasing primary beam energy.

The energy and angle dependence of the spin polarization of secondary electrons ejected from a Cu(100) surface by a polarized incident electron beam of energy 14, 50, and 100 eV has been investigated. At energies approaching the incident beam energy the secondary-electron polarization is comparable to that of the incident beam. The polarization decreases with decreasing secondary-electron energy, however, and at the lowest energies approaches zero. The data are interpreted in terms of the fractional contributions of rediffused primary and true secondary electrons to the total secondary-electron current.