At low temperatures, spin dynamics in ideal spin ice is due mainly to dilute, thermally excited magnetic monopole excitations. I consider how these will affect the dynamics of a nuclear spin (the same theory applies to muon spin resonance if implanted muons do not diffuse). Up to the time scale for nearby monopoles to be rearranged, a stretched-exponential form of the relaxation functions is expected. I work out the expected exponent in that exponential and the formulas for the T1 (longitudinal) and T2 (dephasing) relaxations, as a function of the monopole density. Experimental NMR is incompatible with the predictions and I suggest is due to magnetic impurities.
@article{arxiv.1210.8137,
title = {NMR relaxation in spin ice due to diffusing emergent monopoles},
author = {Christopher L. Henley},
journal= {arXiv preprint arXiv:1210.8137},
year = {2012}
}