Atomic coexistence of superconductivity and incommensurate magnetic order in the pnictide Ba(Fe1-xCox)2As2

As-75 nuclear magnetic resonance (NMR) and susceptiblity were measured in a Ba(Fe1-xCox)(2)As-2 single crystal for x=6%. NMR spectra and relaxation rates allow to show that all Fe sites experience an incommensurate magnetic ordering below T=31 K. Comparison with undoped compound allows to estimate a typical moment of 0.05 mu(B). Anisotropy of the NMR widths can be interpreted using a model of incommensurability with a wave vector (1/2-epsilon,0, l) with epsilon of the order of 0.04. Below T-C=21.8 K, a full volume superconductivity develops as shown by susceptibility and relaxation rate, and magnetic order remains unaffected, demonstrating coexistence of both states on each Fe site.