Magnetic aftereffect in spring magnets and the Preisach model of hysteresis

Magnetic viscosity measurements an NdFeB spring-magnets are interpreted by means of a thermodynamic generalization of the Preisach hysteresis model. The model correctly predicts the observed decay of magnetization and clarifies the connection between anomalous, non-monotone after-effect aad applied field history, Comparison between theory and experiments permits one to estimate the after-effect activation volume, d(3) approximate to (12 nm)(3), anti the attempt frequency 1/tau v similar to 10(10) s(-1).