Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 77: Electronic structure I

O 77.2: Talk

Thursday, March 29, 2012, 16:15–16:30, MA 043

Investigation of the hybridization between the unoccupied Shockley surface state and bulk electronic states on Cu(111) — •Aimo Winkelmann, A. Akin Ünal, Christian Tusche, Cheng-Tien Chiang, Safia Ouazi, Sebastian Wedekind, Masaki Takada, Dirk Sander, Jürgen Henk, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Halle

Shockley surface states and image-potential states in the bulk L-gap of the (111) surfaces of Cu, Ag, and Au are well-known models for the study of quasi-two-dimensional electron systems. We have applied k-resolved multiphoton photoemission using a momentum microscope, scanning tunneling spectroscopy using Fourier-transformation and Bessel-function fitting, together with first-principles electronic structure calculations to determine the dispersion of the occupied and unoccupied Shockley surface state of Cu(111). We verify that the dispersion of this state deviates significantly from the paradigmatic parabolic behavior of quasi-free electrons with increasing energy above the Fermi level [1]. Based on our calculations, we ascribe this deviation to the shift of the spectral weight of the surface state into the bulk, and of bulk states toward the surface, which leads to an enhanced hybridization between the states with increasing energy.

[1] A.A. Ünal, C. Tusche, S. Ouazi, S. Wedekind, C.-T. Chiang, A. Winkelmann, D. Sander, J. Henk, J. Kirschner Phys. Rev. B 84, 073107 (2011)