Superparamagnetic relaxation of weakly interacting particles

The influence of particle interactions on the superparamagnetic relaxation time has been studied by M\"ossbauer spectroscopy in samples of maghemite (y-${\mathrm{Fe}}_{2}$${\mathrm{O}}_{3}$) with different particle sizes and particle separations. it is found that the relaxation time decreases with decreasing particle interactions. A new model for the influence of interactions on the superparamagetic relaxation has been derived and it is shown that this model can explain the observations.