Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 4: Elektronische Struktur I

O 4.6: Vortrag

Montag, 24. März 2003, 12:30–12:45, FOE/ANOR

Local Electronic Structure of the Si(111)–(3×1)–Li Surface as seen by β–NMR — •C. Bromberger, H. J. Jänsch, O. Kühlert, R. Schillinger, and D. Fick — Philipps-Universität, Fachbereich Physik and Zentrum für Materialwissenschaften, D-35032 Marburg, Germany

The ⁸Li surface β–NMR method is used to investigate the local electronic structure of the Li induced Si(111)-(3×1) surface reconstruction. The measured nuclear spin relaxation rate provides information about the local density of states at the Fermi energy and about diffusion properties of the Li on the surface. For a semiconducting surface the free electron driven nuclear spin relaxation rate 1/T₁ should vanish as there is no electron density at the Fermi energy.

Several Li coverages and thus different sizes of (3×1) reconstructed islands on the surface are examined. Near the coverage of the fully reconstructed surface a vanishing relaxation rate 1/T₁ is found at a temperature of 100 K confirming theoretical predictions of the honeycomb–chain–channel (HCC) model [1]. For higher coverages a metallic No-dqKorringaNo-dq like behaviour is found.

At higher temperatures a nonlinear temperature dependence of the relaxation rate is found. This indicates additional nuclear spin relaxation induced by diffusion on the surface.

Supported by the Deutsche Forschungsgemeinschaft (DFG), Bonn.

[1] S. C. Erwin and H. H. Weitering. Phys. Rev. Lett. 80, 1678 (1998)