SUPERCONDUCTING PROPERTIES OF NA-DOPED C-60 PREPARED FROM SODIUM-AZIDE

The Na-doped C-60 Superconductor prepared from sodium azide (NaN3) wer e systematically studied. Superconducting (SC) transition temperature (T-c) was evaluated to be 12-17 K from the low-field signal (LFS) of m icrowave absorption (MA) measurement. Several parameters such as criti cal field of the Josephson junction, the bulk H-c1(0) and H-c2(0), the London penetration depth and coherence length were estimated from LFS and SQUID experiments. The Pauli contribution increases with increasi ng SC volume fraction, but Curie spins are still detected at the low t emperature even in the best sample with 38% of SC volume fraction.