Berlin 2012 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 42: Superconductivity: Fabrication, Properties, Electronic Structure
TT 42.8: Talk
Thursday, March 29, 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 (Kxpicene) using photoemission and density-functional calculations.
Theoretically we have investigated compounds of Kxpicene 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.