The virtual bound states of Fe in AuFe studied by photoemission

By using synchrotron radiation photoemission with photon energies near to the Cooper minimum of Au the authors have detected virtual bound states (VBS) in Au90Fe10. A VBS peaking 0.7 eV below the Fermi energy is attributed to Fe minority states. Less intense features are observed at about 2.3 eV, 4-5.5 eV and 7.3 eV below the Fermi energy, close to the edges of the Au 5d bands, which they suggest are due to the Fe majority states broadened by strong hybridization with the Au valence band. These observations agree with the Friedel-Anderson model which predicts nondegenerate virtual levels with the majority spin population completely occupied and with the minority states spanning the Fermi level.