Strong electronic correlations in LixZnPc organic metals

Nuclear magnetic resonance, electron paramagnetic resonance and magnetization measurements show that bulk LixZnPc are strongly correlated one-dimensional metals. The temperature dependence of the nuclear spin-lattice relaxation rate 1/T1 and of the static uniform susceptibility chi_S on approaching room temperature are characteristic of a Fermi liquid. Moreover, while for x around 2 the electrons are delocalized down to low temperature, for x-> 4 a tendency towards localization is noticed upon cooling, yielding an increase both in 1/T1 and chi_s. The x dependence of the effective density of states at the Fermi level D(EF) displays a sharp enhancement for x=2, at the half filling of the ZnPc lowest unoccupied molecular orbitals. This suggests that LixZnPc is on the edge of a metal-insulator transition where enhanced superconducting fluctuations could develop