GHz transmission through beta(t)-(BEDT-TTF)(2)I-3 thin film; possible indication of phase coherence above T-c.

It has recently been proposed [1] that the thermal destruction of supercond uctivity in under-doped cuprate systems is not by the classical mechanism, where the thermal energy exceeds the pair binding energy. Instead, thermall y generated topological defects destroy the phase coherence necessary for o bservation of the macroscopic phenomenon of superconductivity, namely p --> 0 and M/H --> -1. Experimental evidence for this short-range phase coheren ce above T-c is provided by probing the conductivity at frequencies compara ble to the phase correlation time. Magnetoresistance studies of thin film b eta (t)-(BEDT-TTF)(2)I-3 show the onset of superconductivity at 4 K. The tr ansition is incomplete, with finite resistivity at 500 mK, presumably due t o impurities and growth defects. Here we report the temperature-dependent c onductivity at harmonics of 95 GHz, which, in an analogous manner to the cu prate systems shows a peak above T-c. We propose that this increased absorp tion is due to pair formation on a time scale limited by topological defect s.