On the grain size dependence of the behavicur of fine magnetic particles in rocks

The grain size dependence of the ratio of saturation remanent magnetization to saturation magnetization (J _R :J _S ), weak field susceptibility (X ₀), thermoremanent magnetization (TRM) and its stability against AF demagnetization are interpreted in terms of nucleation theory. It is concluded that each of these parameters exhibits grain size dependence due to two effects. The first is the increasing difficulty with which domain walls are neucleated as grain size decreases. The second is an intrinsic grain size dependence of the parameters in multidomain particles.