Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 12: Nanostructures at Surfaces II (Wires, Tubes)

O 12.1: Talk

Monday, March 26, 2007, 14:15–14:30, H36

Spin-Split Bands in a One-Dimensional Chain Structure — •Ingo Barke, Fan Zheng, Tilman Rügheimer, and Franz Himpsel — Dept. of Physics, University of Wisconsin Madison, 1150 University Ave, Madison, WI 53706, USA

Gold atom chains on vicinal Si(111) surfaces exhibit an unusual doublet of one-dimensional half-filled bands, whose origin has remained uncertain. The splitting is identified by angle-resolved photoemission as a spin splitting induced by the spin-orbit interaction (Rashba effect), in agreement with a theoretical prediction by Sánchez-Portal et al. [1]. This interaction leads to a characteristic pattern of avoided band crossings at a superlattice zone boundary [2]. Two out of four crossings are avoided, with a mini-gap E_G = 85 meV and a k-offset of 0.05 Å⁻¹. The finding solves a long-standing puzzle about the origin of split bands observed in a whole class of atomic chains and is essential for the analysis of their fractional electron count.

The work was supported by the NSF under Awards No. DMR-0240937 and DMR-0084402 (SRC). IB was supported by the German Academic Exchange Service (DAAD) and TKR by the Studienstiftung des Deutschen Volkes.

[1] D. Sánchez-Portal, S. Riikonen, and R. M. Martin, Phys. Rev. Lett. 93, 146803 (2004).

[2] I. Barke, Fan Zheng, T. K. Rügheimer, and F. J. Himpsel, Phys. Rev. Lett. 97, 226405 (2006).