Phase diagram study of Fulleride family

Abstract

The phase diagram of the Fulleride compounds is studied as a function of n, i.e. the band filling of the LUMO or HOMO energy band, depending on the nature of the electron or hole doping, performed either chemically or by an electric field effect. We discuss the role of strong electron–electron correlation, related to electron–vibron interaction and Jahn–Teller distorsion. Superconducting coupling is expected for odd values of n and is expected to be strongest for n=3 in electron doped systems. We take into account the correlated nature of the electron Fermi liquid, which should exhibit a pseudogap phenomenon. Superconductivity is discussed within a strong coupling approach. We show that T c( n) decrease away from n=3 on both sides of this maximum. Moreover, for even values of n, we obtain that the system is the neighbourhood of metal–insulator transition. The case of hole doping, although chemically unaccessible is also discussed.