Theory for the AnomalousM4,5VVAuger Spectrum for Dilute Palladium in Silver

A model Hamiltonian is introduced for an impurity in a filled-band host, where the intraatomic electron interaction $U$ on the impurity site is included. The Auger spectrum ending in two holes in the valence band ($\mathrm{VV}$) is solved exactly for the impurity. For a certain range of values of $U$ there is besides the normal Cini-Sawatzky quasiatomic peak a new discrete twohole state at much lower binding energy. This solution is used to explain the strong anomaly of the Pd $M_{4,5}\mathrm{VV}$ spectrum in $\mathrm{Ag}\mathrm{Pd}$ alloys.