Spectroscopy on highly-correlated organic conductors
Alisa Chernenkaya (Institut für Physik)

Organic conductors are a large class of strongly-correlated low-dimensional materials, exhibiting variety of fundamental phenomena. Some of these materials are close to wide implementation in industry as components for electronics and alternative power engineering and all of the organic conductors are interesting for fundamental research because all these materials are synthetic and, thus, do not occur naturally. The present work addresses the fundamental questions of electronic structure investigations and its correlation to other known properties of the organic materials. Following this goal, the phase characterization of the (DOEO)4[HgBr4]·TCE organic charge transfer complex was performed based on spectroscopic data compared to resistivity, magnetic susceptibility and electron spin resonance. Furthermore, the electronic structure of the unoccupied states in TTF-TCNQ organic metal crystals, which develop with cooling, suggests band gap opening at the Peierls transitions. Additionally, pre-transitional structural fluctuation of the acceptor (pyramidalization of TCNQ) was observed. Two more charge transfer organic complexes were investigated in scope of the present work: DTBDT-TCNQ and DTBDT-F4TCNQ. Two different mechanisms of the process of charge transfer were found in these familiar compounds with the preferable channel on the cyano groups for the first complex and the benzene ring of the acceptor for the latter