Synthetic Metals, 41-43 (1991) 2119-2122 2119 TEMPERATURE DEPENDENT HALL COEFFICIENT OF THE ORGANIC SUPERCONDUCTOR ~-DI(BIS(ETRYLENEDITHIOLO)TETRATHIAFULVALENE)TRIIODIDE, ~-(BEDT-TTF)2I 3 B.Korin-Hamzid, L.ForrO and J.R.Cooper Institute of Physics of the University, POB 304, 41000 Zagreb, Yugoslavia ABSTRACT We report Hall effect data (R H) for two single crystals of the organic superconductor E-(BEDT-TTF)213 in the low Tc phase (EL). An unexpected temperature dependence is obtained with a broad maximum in R H near 40K. A possible interpretation in terms of electron-electron scattering is discussed. INTRODUCTION The organic superconductor E-(BEDT-TTF)213, shows several interesting properties [13: it has a low (EL) and high (EH) T c superconducting phases with T = 1.2K and 8K respectively, unusual structural phase transitions and c displays Shubnikov de Haas oscillations in high magnetic fields [23. The understanding of some basic properties is still incomplete. Hall measurements are less common for organic conductors because the crystals are small and there are difficulties in making proper noise-free contacts. The common feature of the available data in quasi one- dimensional conductors (i.e.two chain systems) e.g. TTF-TCNQ [3J and HMTSF-TCNQ ~4]is that RH is temperature dependent in the metallic phase, much above the transitions to a Peierls semiconductor or to a semimetallic state. This behaviour was attributed by M.Weger [3~ to a dimensional crossover i.e. to a diffusive-coherent transition between the chains. Although E-(BEDT-TTF)213 is a single chain system it is unusual in that it has less conductivity anisotropy, than the Bechgaard salts, and there is probably no diffusive-coherent transition in the ab plane. Indeed Bulaevskii has convincingly argued that at all temperatures the conductivity is dominated by electron-electron Umklapp scattering over a closed FS [1]. The Hall data reported here do show considerable temperature dependence. The results and discussion in more details are published in ref.5. Independent study of DC Hall effect of the low T c (EL) state is published in ref.6. 0379-6779/91/$3.50 © Elsevier Sequoia/Printed in The Netherland~