Measurement of magnetic viscosity in a Stoner-Wohlfarth material

A Stoner-Wohlfarth model has been used to simulate conventional magnetic viscosity experiments. The magnetic viscosity parameter Lambda was found to vary depending on the method used for measurement of the irreversible magnetisation. The difference in Lambda is found to be related to a parameter eta which describes the dependence of reversible magnetisation on irreversible magnetisation. The correct value of Lambda at any field has been related to the population of particles which reverse at that field and it is revealed that distributions of volume and orientation can obscure the interpretation of the measured Lambda. Thus the measurement of Lambda as an indicator of reversal mechanism is questioned.