Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 29: Symposium: Surface Spectroscopy on Kondo Systems I (Invited Speakers: Wolf-Dieter Schneider, Fakher Assaad, Serguei Molodtsov)

O 29.1: Hauptvortrag (ohne Erstattung)

Dienstag, 26. Februar 2008, 11:15–11:45, HE 101

From single magnetic adatoms to two-dimensional Kondo lattices: A local view — •Wolf-Dieter Schneider — EPFL, Institut de Physique des Nanostructures, CH-1015 Lausanne, Switzerland

The unique ability of scanning tunneling microscopy and spectroscopy to address an individual atom on a surface has contributed considerably to our understanding of fundamental excitations and interactions at the atomic level. Here we present a few case studies from our laboratory. These include the detection of the Kondo effect at magnetic adatoms [1], the observation of very-low-energy adsorbate vibrations [2] revealing a surprising similarity with the spectroscopic signatures of Kondo scattering and spin-flip excitations, the manifestation of local disorder within a Ce-adatom superlattice on Ag(111) in its two-dimensional (2D) electronic bandstructure, and the 2D melting via a hexatic phase of a Ce-adatom superlattice on Cu(111). In such superlattices, depending on the relative strength of Kondo scattering versus RKKY interactions, ferromagnetic or antiferromagnetic adatom pairs at different separations may be formed leading to exciting magnetic properties of such artificial nanostructures. These results provide illustrative examples in the emerging fields of nanoscience and nanotechnology for the characterisation and the controlled engineering of physical properties at the single atom level.

[1] J. Li, W.-D. Schneider, R. Berndt, and B. Delley, Phys. Rev. Lett. 80, 2893 (1998).

[2] M. Pivetta, M. Ternes, F. Patthey, and W.-D. Schneider, Phys. Rev. Lett. 99, 126104 (2007).