Regensburg 2000 – wissenschaftliches Programm
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AM: Magnetismus
AM 19: Spektroskopie I
AM 19.2: Vortrag
Donnerstag, 30. März 2000, 10:00–10:15, H22
Lifetime and correlation effects in photoemission from the Gd valence band — •M.C. Malagoli1, K. Maiti1, E. Magnano2, A. Dallmeyer1, and C. Carbone1 — 1Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany — 2Laboratorio Nazionale TASC, Istituto Nazionale per la Fisica della Materia, Padriciano 99, I-34012 Trieste, Italy
The photoemission spectra of the Gd-(5d6s) valence bands display anomalously broad structures with only a very weak energy dispersion as a function of the photon energy. These observations have been previously interpreted as an evidence for a significant band narrowing due to electron correlation effects. We have reinvestigated the exchange-split band structure of the Gd-(5d6s) valence states by using angle-resolved photoemission with spin analysis. The unusual broadening of the spectral lineshapes is found to result from the superposition of strongly dispersive and of non-dispersive components in each of the two spin-resolved photoemission channels. Strong momentum broadening associated to the short photoelectron lifetime in Gd is shown to explain the photoemission spectra and their apparent discrepancy with band structure calculations.