Band structure dependence of hot-electron lifetimes in a Pb/Cu(111) quantum-well system

S. Mathias, A. Ruffing, F. Deicke, M. Wiesenmayer, M. Aeschlimann, and M. Bauer
Phys. Rev. B 81, 155429 – Published 14 April 2010

Abstract

The band structure dependence of the inelastic lifetime of electrons is investigated in a Pb quantum-well system on a Cu(111) substrate with femtosecond time- and angle-resolved two-photon photoemission. For a single monolayer of Pb on Cu(111), we find an unoccupied quantum-well state with a free-electron-like parabolic dispersion around the Γ¯ point and with negative dispersion for finite momentum. Our investigation of this state is a momentum-dependent study of hot-electron lifetimes in a quantum-well system. We demonstrate the importance of intrasubband-scattering processes for the decay of hot electrons at finite momentum. Furthermore, we find that the competition between intersubband- and intrasubband-scattering processes directly induces a momentum anisotropy in the hot-electron lifetimes. This momentum anisotropy is strongly dependent on the specific electronic band dispersion. We compare our findings with previous investigations of ultrafast electron dynamics in model-like surface-state systems and with ultrafast electron dynamics in Pb full-bulk material. Our findings suggest that the peculiar electronic structure of quantum-well systems can be used to tune ultrafast dynamical properties in metals.

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  • Received 12 November 2009

DOI:https://doi.org/10.1103/PhysRevB.81.155429

©2010 American Physical Society

Authors & Affiliations

S. Mathias1,2,*, A. Ruffing1, F. Deicke1, M. Wiesenmayer3, M. Aeschlimann1, and M. Bauer3

  • 1Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany
  • 2JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440, USA
  • 3Institut für Experimentelle und Angewandte Physik, Universität Kiel, 24098 Kiel, Germany

  • *smathias@physik.uni-kl.de

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Vol. 81, Iss. 15 — 15 April 2010

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