Magnetic viscosity and switching field distributions in recording media

The relationship between the coefficient of magnetic viscosity S and the switching field distribution (SFD) of recording media is examined. Two samples of magnetic tape have been measured and a theory devised showing the interrelationship between S and the SFD. Good agreement between theory and experiment is reported, taking into account the approximations necessary in the derivation. It has been shown that the time-dependence coefficient S can be related to the irreversible susceptibility, defined as the differential of a primary remanence curve.