Dresden 2006 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 6: Electronic Structure and Spectroscopy I

CPP 6.10: Vortrag

Montag, 27. März 2006, 17:00–17:15, ZEU 114

Anisotropy of the transport mechanisms in organic quasi 1D conductors — •David Saez de Jauregui and Elmar Dormann — Physikalisches Institut, Universität Karlsruhe (TH), D-76128 Karlsruhe

Arene radical cation salts (rcs) are synthetic metals consisting of polycyclic aromatic hydrocarbons (i.e. naphthalene, fluoranthene, pyrene or perylene) and inorganic complex anions (i.e. PF₆, AsF₆ or SbF₆) . Due to a π-orbital overlap of the arene molecules and a not completely filled conduction band the rcs are quasi-one dimensional conductors. They perform a Peierls transition between a metallic high temperature phase with a pseudo-gap caused by fluctuations and charge density ground.
These rcs provide excellent model systems for investigations of the transport dynamics, because both the electronic charge as well as the electron spin motion can be detected. Using microwave conductivity measurements and X-band-pulse-ESR techniques with applied static field gradients the electron charge motion and the electron spin diffusion were examined for different orientations and a broad temperature regime below and above the semiconductor-metal phase transition. This was done for rcs with different paramagnetic defect concentrations. The influence of defects is a decrease of the anisotropic behavior of the organic conductors. The real "intrinsic" anisotropy of the electrical conductivity and the spin diffusion coefficient must be derived by extrapolation to vanishing defect concentration.