The use of torque magnetometry in determining particle anisotropy and orientation distributors in magnetic tape materials

A new experimental procedure for determining the orientation and anisotropy of magnetic tape particles using a torque magnetometer to measure the hysteretic loss during forward-reverse cycles of the field orientation is reported. The novelty lies in measuring the loss over small angular cycles (10°). The loss, dependent on both the magnitude and average orientation of the field to the particle alignment axis yields a map of the orientation distribution of the particles and anisotropy fields. The analysis assumes that particles undergoing repeated discontinuous reversals for small angular oscillations of the applied field do so by coherent rotation. Evidence is given for the validity of this assumption.