Spin-resolved photoemission investigation of the c(2x2) and c(3x1) oxygen overlayers on the Fe(110) surface

The oxygen adsorption on the Fe(110) surface has been studied by spin- and angular-resolved photoemission and low-energy electron diffraction techniques. At very low coverage, oxygen adsorbs in a sequence of well-defined ordered structures: a c(2x2) followed by a c(3x1). For the c(2x2) overlayer the oxygen bands show hardly any dispersion along the [1 (1) over bar 0] direction of the surface Brillouin zone. A slightly larger dispersion is instead detected for the c(3 x 1) overlayer. In both cases, the two-dimensional models for the oxygen 2p-derived bands do not seem to be appropriate. The spin-resolved data suggest a considerable interaction with the Fe substrate. A relatively large exchange splitting (Delta(ex)=0.3 eV) is induced on the oxygen 2p bands, indicating a local magnetic moment on the oxygen sites, The considerably different line shape of the O 2p emission in the two spin channels is also an;indication of strong interaction of the oxygen adatoms with the spin-dependent electronic structure of the ferromagnetic substrate. [S0163-1829(98)05444-7].