Photoemission study of quantum confinement by a finite barrier: Cu/Co(wedge)/Cu(100)

Abstract
Quantum confinement is studied with angle-resolved photoemission for ultrathin Cu separated from the Cu(100) substrate by an epitaxial wedge of Co (0–11 Å) that serves as a finite barrier. For 2 ML of Cu, the photoemission intensities of the Cu sp quantum-well (QW) state at 1.6 eV binding energy and the corresponding d-band-derived QW state at 2.4 eV increase rapidly with the thickness of the Co barrier and indicate stronger confinement of the d QW state than of the sp state. Implications for the magnetic coupling and magnetoresistance are discussed.