Orientation of acicular particles in magnetic tape

We present a simple method to determine the orientation distribution of acicular particles in magnetic tape. This result can be used to determine the tape magnetization and the transition width in the presence of a Karlquist field generated by the write head. The particle orientation distribution is determined by a series of measurements on a vibrating sample magnetometer consisting of saturating the tape at successive incremental polar angles, A, away from the ribbon axis, and measuring the remanent magnetization Mr along the ribbon axis after each saturation. Conceptually, particles having their easy axes in the upper half space at an angle greater than 90° from A have their magnetization reversed upon relaxing from saturation. This reduces the tape’s original remanent magnetization along the easy axis. Successive reductions in Mr are entered into an APL program, which computes the corresponding orientation distribution.