  We re-analyze Nuclear Magnetic Resonance (NMR) spectra observed at low
temperatures and high magnetic fields in the field-induced B-phase of CeCoIn5.
The NMR spectra are consistent with incommensurate antiferromagnetic order of
the Ce magnetic moments. However, we find that the spectra of the In(2) sites
depend critically on the direction of the ordered moments, the ordering
wavevector and the symmetry of the hyperfine coupling to the Ce spins. Assuming
isotropic hyperfine coupling, the NMR spectra observed for H||[100] are
consistent with magnetic order with wavevector Q=pi((1+delta)/a,1/a,1/c) and Ce
moments ordered antiferromagnetically along the [100] direction in real space.
If the hyperfine coupling has dipolar symmetry, then the NMR spectra require Ce
moments along the [001] direction. The dipolar scenario is also consistent with
recent neutron scattering measurements that find an ordered moment of 0.15 mu_B
along [001] and Q_n=pi((1+delta)/a,(1+delta)/a,1/c) with incommensuration delta
= 0.12 for field H||[1-10]. Using these parameters, we find that a hyperfine
field with dipolar contribution is consistent with findings from both
experiments. We speculate that the B phase of CeCoIn5 represents an intrinsic
phase of modulated superconductivity and antiferromagnetism that can only
emerge in a highly clean system.
