Comparative experimental study of exchange biased symmetric and antisymmetric dual magnetoresistive read elements

In this work, the advantage of the antisymmetric dual magnetoresistive head (A-DMR) in comparison to the symmetric design (S-DMR), in terms of common mode longitudinal field rejection is demonstrated experimentally. The experiments were conducted at the wafer level. Magnetoresistive hysteresis loops of heads with the top permalloy longitudinally biased by TbCo exchange tabs, defined either by an ion-milling process or by lift-off, are presented. Initialization methods to have the symmetric or the antisymmetric state at low longitudinal applied magnetic fields are described