AVS 53rd International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI-TuA

Paper MI-TuA2
Spin-Polarized Quantum-Well States in Ni/Cu Thin-Film Structures

Tuesday, November 14, 2006, 2:20 pm, Room 2006

Session: Magnetic Thin Films and Multilayers
Presenter: V. Renken, Westfälische Wilhelms-Universität, Germany
Authors: V. Renken, Westfälische Wilhelms-Universität, Germany
D.H. Yu, Australian Nuclear Science and Technology Organisation
M. Donath, Westfälische Wilhelms-Universität, Germany
Correspondent: Click to Email
The unoccupied quantum-well states (QWS) in ultrathin films of Ni on Cu(001) and Cu on Ni/Cu(001) have been investigated by spin- and angle-resolved inverse photoemission. In ferromagnetic Ni films on Cu(001), three spin-polarized quantum-well features are clearly resolved. As predicted by the phase accumulation model, the energies of the QWS increase with increasing Ni overlayer thickness. Eventually they converge to the top of the bulk sp-band at the lower band-gap boundary as a result of a crossover from two- to three-dimensional behavior. In ultrathin Cu films on Ni/Cu(001), QWS in both the Cu and the Ni layers have been experimentally identified. For small Cu coverages up to 2.5 monolayers (ML), discrete QWS within the Cu layers are observed with the expected behavior: they shift to higher energies with increasing Cu thickness. The energetics of the QWS within the Ni layers is not influenced but their intensities are attenuated by the Cu overlayer. For Cu films thicker than about 5 ML, the discrete QWS in Cu cannot be distinguished any more. Only one spectral feature remains: the transition into the Cu sp-band. However, this transition appears at higher energy compared to bulk Cu. Upon further increase of the Cu film thickness, the sp-band transition continuously shifts to lower energies. Finally, for a thickness of more than 20 ML, it approaches the value known from the (001) surface of bulk Cu.