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O: Oberflächenphysik

O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)

O 28.11: Poster

Mittwoch, 10. März 2004, 16:00–19:00, Bereich C

Valence band photoemission spectroscopy of chemically disordered ultrathin Ni_xPd_1−x films on Cu₃Au(100) — •Frank Matthes¹, Liu-Niu Tong¹, Alexej Rzhevskii², and C.M. Schneider² — ¹Leibniz Institut für Festkörper- und Werkstoffforschung Dresden, PF 27 01 16, D-01171 Dresden — ²Institut für Elektronische Eigenschaften, Forschungszentrum Jülich, 52425 Jülich

We have studied the valence band structure of ultrathin Ni_xPd_1−x alloys on a single crystalline Cu3Au(100) substrate. Ni and Pd are isoelectronic, but while Ni is ferromagnetic with an average exchange splitting of 0.3 eV along the Δ direction, Pd exhibits a higher spin orbit coupling (band splitting 0.3 eV). Via the alloy concentration one can conveniently vary the relative weight of these two spin-dependent interactions with profound effects for the electronic structure. We will present first results of our high-resolution photoemission measurements for 15 monolayer thick Ni_xPd_1−x films with different compositions. The measurements were performed along the Δ direction for excitation energies from 16 eV to 40 eV. As a main spectral feature, we observed contributions from bands originating from 3d Ni and 4d Pd electrons near the Fermi energy. This feature only disperses weakly with the excitation energy. Starting with pure Ni films, we observed a broadening of the spectra while increasing the Pd concentration up to 30%. This may be caused by the chemically induced disorder. To distinguish the spin dependent contributions and thus arrive a more detailed interpretation of the photoemission data, we performed for three different Ni rich alloy compositions also spin-resolved photoemission experiments.