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• Strong correlation energies are measured in Auger spectra from Fe ultra-thin films. • Coulomb and exchange interactions are estimated for eg and t 2 g states and both spins. • Exchange coupling is due only to the more itinerant t 2 g electrons. • e g electrons undergo a stronger localization when Fe is coupled to the CoO substrate. • Fe bonded to O does not play relevant role in the magnetic properties at the interface. Angle resolved-Auger photoelectron coincidence spectroscopy (AR-APECS) has been exploited to investigate the role that electron correlation plays in the exchange-coupling at the ferromagnetic/antiferromagnetic interface of a Fe/CoO bilayer grown on Ag(001). The effective correlation energy U eff , usually employed to assess the energy distribution of core-valence-valence Auger spectra, has been experimentally determined for each possible combination of the orbital (e g or t 2 g) and the spin (majority or minority) of the two valence electrons involved in the Auger decay. Coulomb and exchange interactions have been identified and compared with the result obtained on the Fe/Ag system. The presented analysis reveals in the Fe/CoO interface an enhancement of the Coulomb interaction for the e g orbital and of the exchange interaction for the t 2 g orbital with respect to the Fe/Ag case, that can be associated with the stronger electron confinement and to the exchange coupling between the two layers, respectively. [ABSTRACT FROM AUTHOR]