Hopping conductivity in one-dimensional<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ca</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Co</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>single crystals

We studied the electronic conductivity and magnetic properties of quasi-one-dimensional ${\mathrm{Ca}}_{3}{\mathrm{Co}}_{2}{\mathrm{O}}_{6}$ single crystals. The results evidence a variable range hopping conductivity with temperature-induced crossover between one-dimensional (intrachain) and three-dimensional (3D) transport and the opening of a Coulomb gap in the d bands along with the ferromagnetic intrachain ordering. At low temperatures, an applied magnetic field induces a large negative magnetoresistance (MR) in apparent dissociation with the 3D magnetic ordering. 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. Surprising narrow peaks corresponding to a transient resistivity decrease are observed on the MR curves. We discuss these in terms of peculiar in-plane magnetization states in an Ising-like Heisenberg antiferromagnetic triangular lattice during the magnetization reversal.