Electronic properties of the Na(2)AC(60) family (A=K, Rb, Cs)

Electron Spin Resonance(ESR) at ambient and under high pressure and optical reflectivity measurements were used to study the consecutive phase transitions in Na(2)AC(60) family of fulleride compounds. The high temperature fcc phase in all three A=K, Rb, Cs compounds are found to show semi-metallic behaviour. For the first time a peculiar sequence of phase transitions from semi-metallic to metallic to superconducting phases are observed in Na2CsC60. The metallic properties of the polymeric phases in A=K, Rb were established.