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Unoccupied electronic states of icosahedral Al-Pd-Mn quasicrystals: Evidence of image potential resonance and pseudogap

TitleUnoccupied electronic states of icosahedral Al-Pd-Mn quasicrystals: Evidence of image potential resonance and pseudogap
Publication TypeJournal Article
Year of Publication2014
AuthorsManiraj, M, Rai, A, Barman, SR, Krajci, M, Schlagel, DL, Lograsso, TA, Horn, K
JournalPhysical Review B
Volume90
Pagination115407
Date Published09
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000341259600003
Keywordsalloys, density-of-states, dispersion, inverse-photoemission, metal-surfaces, phase, resolution photoemission-spectroscopy, single-crystal
Abstract

We study the unoccupied region of the electronic structure of the fivefold symmetric surface of an icosahedral (i) Al-Pd-Mn quasicrystal. A feature that exhibits parabolic dispersion with an effective mass of (1.15 +/- 0.1)m(e) and tracks the change in the work function is assigned to an image potential resonance because our density functional calculation shows an absence of band gap in the respective energy region. We show that Sn grows pseudomorphically on i-Al-Pd-Mn as predicted by density functional theory calculations, and the energy of the image potential resonance tracks the change in the work function with Sn coverage. The image potential resonance appears much weaker in the spectrum from the related crystalline Al-Pd-Mn surface, demonstrating that its strength is related to the compatibility of the quasiperiodic wave functions in i-Al-Pd-Mn with the free-electron-like image potential states. Our investigation of the energy region immediately above E-F provides unambiguous evidence for the presence of a pseudogap, in agreement with our density functional theory calculations.

DOI10.1103/PhysRevB.90.115407
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