On the measurement of magnetic viscosity

This work is an investigation of the experimental method used for measuring the magnetic viscosity in a hard ferromagnetic material, i.e. the recording of the magnetization under constant applied field and temperature, after the material has been magnetically saturated. It investigates how the experimental results are affected by the initial conditions of the method (saturation field, field change rate and field oscillation prior to its stabilization), and by minor variations of field and temperature during the recording. Based on the arising conclusions and the use of a more complex fitting function of measurements, the accuracy and repeatability of experimental results is improved.

► Magnetic viscosity is affected by initial measurement conditions. ► Minor field deviations prior to its stabilization cause large changes in viscosity. ► Viscosity is strongly dependent on the field change rate from saturation to the measurement field. ► Small changes in field and temperature during the experiment can lead to false measurements. ► Errors in measurements can be eliminated through the use of a proper fitting function.