Europhys. Lett.
Volume 63, Number 5, September 2003
Page(s) 729 - 735
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 November 2003
DOI: 10.1209/epl/i2003-00586-5
Europhys. Lett., 63 (5) , pp. 729-735 (2003)

Probing electron confinement in ultrathin metal films: From spin-polarized quantum-well states to surface resonances

D. H. Yu and M. Donath

Physikalisches Institut, Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany

(Received 19 May 2003; accepted in final form 27 June 2003)

The unoccupied electron states of the sandwich structure $\chem{Cu/Co/Cu(100)}$ have been investigated by spin- and angle-resolved inverse photoemission. Different types of electron states are clearly identified based on the spin-resolved data: spin-polarized quantum-well states within the $\chem{Cu}$ layer, surface states and a surface resonance at the copper/vacuum interface, and bulk-like minority d contributions from the underlying ferromagnetic $\chem{Co}$ layer, which are accessible within the experimental probing depth. The quantum-well states are shown to develop into a surface resonance as a function of the electron momentum. Experimental evidence of this change in electron confinement is a vanishing exchange splitting. The loss of spin polarization is caused by a decoupling of the electron wave function from the ferromagnetic $\chem{Co}$ at the inner interface.

73.21.Fg - Quantum wells.
75.70.Cn - Magnetic properties of interfaces (multilayers, superlattices, heterostructures).
79.60.Dp - Adsorbed layers and thin films.

© EDP Sciences 2003