XVV Auger and APS spectra of Fe-Ni alloys

The two-hole and the two-electron spectra, which are related to the XVV Auger and to the APS spectra, respectively, have been computed for an Fe-Ni alloy of different compositions. A recently proposed theory has been used which, by means of some approximations, is capable of treating the two-particle spectra of a Hubbard-type Hamiltonian in the important case of a not completely filled valence band. In that situation, the role of the Coulomb repulsion between two particles is quite relevant in determining shifts and broadenings of the spectra. The Coulomb correlation results also in a renormalization of the one-particle spectrum. The results show that, while the Auger spectra are contributed to by both spin up and spin down bands, the APS spectra are contributed to only by spin down bands.