Quantum-well or bulklike behaviour of Cu layers on Co

Angle-resolved photoemission was employed to probe the quantum-well behaviour, or the lack of it, of Cu films epitaxially grown on low-index Co substrates. Upon varying the photon energy, films grown on Co(111) exhibited a bulklike continuous dispersion for the sp state, while films grown on Co(100) and Co(100) exhibited nondispersive quantum-well peaks with intensities modulated by the bulk band dispersion. These different behaviours, namely, bulklike versus quantum-well-like, are explained in terms of the band structure. The results are correlated with the magnetic coupling effects in multilayer systems.