Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 77: Methods: Scanning Probe Techniques I

O 77.7: Talk

Thursday, February 28, 2008, 17:00–17:15, MA 041

Metal cross–substitution in the misfit layer compound (PbS)_1.13TaS₂ — •Matthias Kalläne¹, Hans Starnberg², Kai Roßnagel¹, Martin Marczynski-Bühlow¹, Sven Stoltz², and Lutz Kipp¹ — ¹Institute for Experimental and Applied Physics, University of Kiel, D-24098 Kiel, Germany — ²Department of Physics, Göteborg University, SE-412 96 Göteborg, Sweden

Bonding in layered materials is a challenging problem because it includes various types of interactions ranging from strong local covalent bonds over electrostatic interactions to rather weak nonlocal van der Waals forces. Consisting of alternatingly stacked slabs of hexagonally ordered transition metal dichalcogenides (TMDCs) and cubic monochalcogenides, the layered TMDC misfit compounds are hetero–structures with a complex layer–to–layer interface due to the different symmetries of the subsystems. Their incommensurability, the alternation of different layers, and the occurrence of monochalcogen bilayers all act against a low total energy. It is thus surprising that they show such a remarkable stability. To investigate the nature of the interlayer bonding, angle– as well as spatially–resolved photoelectron spectroscopy measurements were performed on the layered misfit compound (PbS)_1.13TaS₂. The results provide direct evidence for metal cross–substitution between the layers which alters the charge balance between alternating layers and can explain the remarkable stability of misfit compounds.

Photoemission experiments were carried out at HASYLAB, MAXLAB, and the ALS. Work supported by DFG FOR 353.