Nuclear Dipolar Interactions in Magnetically Ordered Systems

The dipolar coupling between nuclei in magnetically ordered systems, specifically antiferromagnets, has been studied theoretically and experimentally. In these materials, the timeaveraged local fields "seen" by the nuclei may vary in magnitude and direction. This results in terms in the nuclear dipolar Hamiltonian other than the usual $I_i^z{I}_j^z$ and $I_i^{+}{I}_j^{-}$ contributing to the dynamic width of the nuclear magnetic resonance.