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TT: Fachverband Tiefe Temperaturen

TT 42: Superconductivity: Fabrication, Properties, Electronic Structure

TT 42.8: Vortrag

Donnerstag, 29. März 2012, 17:00–17:15, H 3005

Non-metallicity in potassium-doped picene films — •Andreas Ruff¹, Milan Tomic², Hunpyo Lee², Harald O. Jeschke², Roser Valentí², Michael Sing¹, and Ralph Claessen¹ — ¹Experimentelle Physik 4, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — ²Institut für Theoretische Physik, Goethe-Universität Frankfurt, 60438 Frankfurt am Main, Germany

We have performed a comparative study of the electronic structure of the potassium-doped organic semiconductor picene (K_xpicene) using photoemission and density-functional calculations.

Theoretically we have investigated compounds of K_xpicene with integer x=1,2,3 to clarify the atomic positions of the alkali metal dopants and the resulting bandstructure. Experimentally, we recorded a series of photoemission spectra with doping concentrations in the range of x=0...3. While the ab initio electronic structure calculations reveal metallic behavior for K₁picene and K₃picene and semiconducting properties for K₂picene, the system remains insulating for all doping concentrations x from the spectroscopic view.

We discuss this discrepancy in terms of possible strong electron correlation effects and/or phonons as well as the occurrence of chemical phase separation in our samples.