Experimental and Model Theoretical Dispersions of Unoccupied Metallic Quantum Well States in the Cu/fccCo/Cu(100) System

The dispersion with parallel momentum of unoccupied metallic quantum well states in the Cu/fccCo/Cu(100) system has been measured using inverse photoemission and modeled using a phase analysis approach. A flat band near the Fermi level is observed near the neck of the Cu Fermi surface along the $\overline{\Gamma X}$ direction. Appearance of the state coincides with a hybridization gap in the minority spin bands of the underlying Co and its influence on the phase and strength of the short period magnetic coupling in this and similar systems is discussed.