Theory of Anhysteretic Remanent Magnetization for Randomly Spatially Oriented Uniaxial Single-Domain Particles

A generalization of the theory of formation of anhysteretic remanent magnetization (ARM) is generalized for noninteracting randomly spatially oriented uniaxial single-domain particles. It is shown that approximate expressions for the ARM intensity, which have been proposed in (Schcherbakov and Shcherbakova, 1977; Victora, 1989; Egli, 2002), are quite admissible for obtaining estimates. However, our calculations have revealed a striking discrepancy between theoretical conclusions and experimental results. It follows from the theory that the ARM intensity exceeds by several times the thermoremanent magnetization (TRM) intensity, while experiments lead to the inverse relation between ARM and TRM. For resolving this paradox and for explaining the mechanism of ARM formation in rocks, it is necessary to supplement the theory proposed here by including the magnetostatic interactions; as regards experimental verification, it is necessary to carry out experiments with ARM and TRM for ensembles of noninteracting grains (i.e., for their very low concentration in the sample).