Charge redistribution and Fermi surface modification on Be(0001)

Vobornik, Ivana1; Fujii, Jun1; Hochstrasser, Michael2; Krizmancic, Damjan1; Viol, Carlos1; Fabris, Stefano1; Baroni, Stefano1; Panaccione, Giancarlo1; Rossi, Giorgio1 1Italy; 2Switzerland

Metallic properties of a material are determined by the shape and topology of its Fermi surface, which at absolute zero temperature separates occupied and unoccupied electronic states. The properties of metallic surfaces often differ from the bulk. The discontinuity in the lattice periodic potential may lead to surface relaxation and/or reconstruction and creation of new electronic states - surface states.
By surface sensitive angle resolved photoemission based Fermi surface tomography we quantified the modification of the Fermi surface of beryllium on the (0001) surface that hosts two surface states and a surface resonance. We find >35% reduction in the volume enclosed by the remnant bulk-like Fermi surface which is consistent with the charge transfer to the surface states estimated from the area within their two dimensional Fermi contours. The experimental finding is further supported by the density functional theory calculations. This result represents the first quantification of the charge redistribution on a natural surface termination. Our method and results have implications not only for the characterization of natural solid surfaces, but also for artificial nanostructures where the understanding of an interplay between low dimensional and three dimensional electronic properties is crucial.

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