The coefficient of magnetic viscosity

Abstract

The coefficient S characterising the time dependence of the magnetisation of a magnetic material is calculated in terms of the irreversible susceptibility chi irr are discussed in relation to experiment and computations. The Barbier plot of Hf against the coercive force Hc is shown to agree quantitatively with theoretical models of Hc. Correlation effects are discussed on the same basis as occurs in interpretations of the Vogel-Fulcher law of spin glasses.