Measurement of magnetic viscosity in NdFeB

Magnetic viscosity has been investigated in four samples of melt-quenched and sintered NdFeB. The irreversible magnetization has been measured using two different techniques based on measurements of the DCD remanence curve and the reversible susceptibility, The difference in the value of Lambda (sometimes known as the fluctuation field H-f) measured by these two techniques has been related to a new parameter eta which describes the dependence of reversible magnetization on irreversible magnetization. The behaviour of eta for the melt-quenched and sintered samples is compared with the behaviour expected for an idealised Stoner-Wohlfarth system.