Magnetization in recorded tape

We have measured the in-plane magnetization and the perpendicular magnetization which 10-μm-thick tape of γ-Fe2O3particles acquires on passing through the field of a head driven with direct current. The perpendicular component of the head field has two adverse effects on the remanent state at the surface of the tape closest to the head. First, it induces a perpendicular component of magnetization which leads to asymmetry in the output pulse. Second, it leads to a reduction in the in-plane magnetization which reduces the signal output level at high recording densities. The perpendicular moment can be ≥5% of the in-plane moment in the normal writing current range of the head. In the same current range the reduction in in-plane moment represents about 5% of the tape's maximum remanent moment.