GAP SYMMETRY OF ORGANIC SUPERCONDUCTOR KAPPA-(MDT-TTF)(2)AUI2 DETERMINED BY SPECIFIC-HEAT

We have made precise measurement of specific heat C of the organic sup erconductor, (MDT-TTF)(2)AuI2 (T-c = 4.15 K) at low temperatures down to 0.5 K at zero field and at several fields up to 1 T. Owing to the l attice softness, the specific heat, which does not follow simple Debye T-3 law, is dominant over electronic part. Subtracting the lattice pa rt, we clarified the specific heat jump at T-c and determined the temp erature dependence below T-c with the special interest of the mechanis m of the superconductivity in this material. We found that the differe nce of C between superconducting and normal state follows the temperat ure dependence of the BCS framework. This is consistent with the concl usion of the previous H-1-NMR study.