Electron spin resonance study of the polymeric phase of Na2RbC60

The structural and electronic properties of the polymeric phase of Na2RbC60 which comprises of C-C bridged C-60(3-) chains have been studied between 4 10 and 4 K with the electron spin resonance (ESR) technique. On cooling, th e polymeric phase starts growing below similar to 250 K. Its fraction reach es a maximum at similar to 190 K, where around 55% of the monomeric cubic p hase have transformed to the polymer. The temperature dependence of the ESR susceptibility suggests that the Na2RbC60 polymer is conducting down to 3 K. The ESR results exclude the possibility of the existence of a ground-sta te instability and the formation of either a spin-density-wave (SDW) or a c harge-density-wave (CDW) state. [S0163-1829(99)01530-1].