Physical properties in the normal state of the molecular superconductor Κ-(BEDT)2Cu2(CN)3

We have investigated the electrical, spectroscopic and magnetic properties of the K-phase molecular conductor K-(BEDT)2Cu2(CN)3 between room temperature and the liquid He4 temperature range. We have shown that an intermittent superconducting material is present around or below 4 K which presents above this temperature limited spin fluctuations. The influence of disorder inside the anionic layers is discussed with respect to the X-ray crystal structure, and also the intrinsic effects due to temperature or pressure to explain this situation. Finally, the specific behaviour of the ESR linewidth at low temperature is analysed as a magnetic precursor regime of the supposed superconducting ground state. (orig.)