THEORY OF AUGER-XVV SPECTRA OF SOLIDS - MANY-BODY EFFECTS IN INCOMPLETELY FILLED BANDS

The availability of empty electron states above the Fermi level and the presence of strong intra-atomic correlations may be expected to lead to new features in the Auger XVV spectra of conduction bands. Here, the qualitative aspects of the problem are studied within a simplified model. The case of a low equilibrium hole density nh in the band is considered in detail and the various propagators are calculated in a low density approximation. It is found that correlation and shake up effects can be approximately factored out and the singularity exponent relevant to the problem is linear in nh. In the single particle density of states we find a peak in the high binding energy side, which appears to be consistent with the experimental XPS spectra of Fe, Co and Ni. The Auger XVV spectra are obtained in the same approximation. As in the case of closed bands (nh = 0) two-hole resonances appear in the spectra provided that intra-atomic correlations are strong enough (quasiatomic case), but the condition for their occurrence is found to involve the total band width, rather than the width of the occupied portion of the band only. Moreover, even in the quasiatomic case, the resonances have a width that is related to the energy difference between the top of the band and the Fermi level. © 1979.