Characterization of viscous remanent magnetization in single‐ and multi‐domain magnetite grains

Viscous remanent magnetization acquisition and decay coefficients are shown to be strongly affected by the previous magnetic history of the samples. Demagnetization of coarse grain, multi‐domain, magnetite samples using alternating magnetic fields causes a sharp reduction in the ability to acquire viscous magnetization. VRM acquisition in single‐domain particles is not affected by AF demagnetization but is sensitive to the amount of time the sample is kept in zero magnetic field storage prior to applying the VRM field. VRM acquisition coefficients are strongly dependent on magnetic grain size with high values at both very small and very large grain diameters.