The effect of nearest-neighbour interactions between hopping spins on nuclear spin relaxation in solids

Abstract

The authors investigate the effect of pairwise nearest-neighbour interactions on T1-1, the spin-lattice relaxation rate due to magnetic dipolar coupling between diffusion spins. The method used is an extension of the analytic/Monte Carlo procedure introduced by Faux, Ross and Sholl (1986). Results are obtained for a range of spin concentrations and interaction energies (both attractive and repulsive) for the SC and FCC lattice. It is shown that the peak height varies linearly with nearest-neighbour spin density over the range of interaction energies considered. Interpolation allows the relaxation rate to be generated as a function of reciprocal temperature for a general nearest-neighbour interaction energy. It is therefore shown that, if T1-1 is plotted as a function of reciprocal temperature, the presence of interactions can lead to different gradients on either side of the T1-1 peak.