Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 34: Methods: Atomic and Electronic Structure I

O 34.5: Vortrag

Dienstag, 27. März 2007, 16:45–17:00, H42

Giant spin-orbit splitting in the surface alloy Bi/Ag(111): A theoretical explanation — •Jürgen Henk, Arthur Ernst, and Patrick Bruno — Max-Planck-Institut für Mikrostrukturphysik, Halle (Saale)

The Rashba-Bychkov effect at (111) surfaces of noble metals, in particular Au, results in a spin-orbit splitting of the L-gap surface states, in analogy to a two-dimensional electron gas. Recent photoemission experiments for the surface alloy Bi/Ag(111) also found a spin-orbit splitting but the size of the splitting is unexpectedly large (Chr. Ast et al, cond-mat/0509509). Usual explanations of the effect by the atomic contribution to the spin-orbit coupling and by the gradient of the surface-barrier potential fail.

Relativistic first-principles calculations give strong support for a new mechanism. The interplay of the conventional Rashba-Bychkov contribution to the spin-orbit interaction and the in-plane gradient of the surface potential leads to the giant splitting of the Bi-derived surface states. In addition, the spin polarization of these states is considerably rotated out of the surface plane. The latter prediction suggests investigations by means of spin-resolved photoemission.