Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 65: Methods: Theory and Experiment

O 65.5: Vortrag

Donnerstag, 28. Februar 2008, 13:00–13:15, MA 141

Spin-orbit split two-dimensional electron gas with tunable Rashba and Fermi energy — •Christian R. Ast¹, Daniela Pacile², Luca Moreschini², Mihaela Falub², Marco Papagno², Klaus Kern^1,2, Marco Grioni², Jürgen Henk³, Arthur Ernst³, Sergey Ostanin³, and Patrick Bruno³ — ¹MPI für Festkörperforschung, Stuttgart, Germany — ²EPFL, Lausanne, Switzerland — ³MPI für Mikrostrukturphysik, Halle, Germany

In the Rashba-Bychkov-Model the strength of the spin-orbit splitting — the Rashba energy E_R — introduces a new energy scale influencing the electronic structure and competing against other energy scales, such as the Fermi energy E_F. However, in most of the known systems up to now the Rashba energy is a perturbative correction. We demonstrate that it is possible to tune the Rashba energy and the Fermi energy in a two-dimensional electron gas by a controlled change of the stoichiometry of an artificial surface alloy. In the Bi_xPb_1−x/Ag(111) surface alloy the spin-orbit interaction maintains a strong influence on the band dispersion for arbitrary Bi concentration x, as is shown by angle-resolved photoelectron spectroscopy. The Rashba energy E_R and the Fermi energy E_F can be tuned to achieve values larger than one for the ratio E_R/E_F, which opens up the possibility for observing new phenomena, such as corrections to the Fermi liquid or a superconducting state. Relativistic first-principles calculations explain the experimental findings.