SUPERCONDUCTIVITY OF C60 COMPOUNDS

A series of C60 compounds is prepared using several K-Tl, Rb-Tl and Cs -Bi alloys in order to determine their superconducting properties. Sam ples with the nominal composition (RbTl1.5)3C60 show a superconducting onset temperature of 27.5 K. The temperature dependence of the magnet ic penetration depth agrees with theoretical expressions derived for w eak-coupled BCS-type superconductors in the clean local limit. The B(C 2) (T) curves show a positive curvature near T(C). Susceptibility, X-r ay and C-13 NMR measurements indicate a decomposition of the binary al loy during the preparation procedure and the presence of metallic T1 i n the sample.