Angular dependence of magnetization in recording media

A high magnetic field (11 kG) is applied in the plane of a piece of magnetic recording tape at an arbitrary angle set with respect to the tape direction. This profoundly alters the response of the tape at lower fields. The component of the magnetization along the field direction is observed while rotating the tape about an axis perpendicular to its plane after lowering the field directly from high field at angle θ_set. Experiments are repeated for a wide range of measuring fields and choices of θ_set. In the range of measuring fields for which rotational hysteresis is a prominent effect, it is found that right handed and left handed rotations are not equivalent except for particular choices of θ_set. The remanent magnetic moment has a magnitude and direction that depends on θ_set. The remanence data is explicable using a distribution of easy axes and the assumption that the high field selects the nearer of the two directions along the easy axis for each particle. Distributions are deduced for four types of commercial magnetic tapes