Electronic transport in one-dimensional Ca3Co2O6 single crystal

The electronic conductivity study of the quasi-one-dimensional Ca3Co2O6 single crystal evidences a Variable Range Hopping conductivity with temperature-induced crossover between 1D and 3D transport and the opening of a Coulomb gap in the d bands along with the ferromagnetic intra-chain ordering. A large negative magneto-resistance is observed at low temperatures. Both spin-dependent hopping and field-induced suppression of the Coulomb gap are discussed. The electronic hopping parameters we infer agree remarkably with the accessible Co sites. Finally, we present the first electronic noise study in a one-dimensional frustrated magnetic single crystal and we discuss the interplay between the low temperature 3D magnetic ordering and the spin-dependent hopping conductivity on the Co sites.