AP pinned PtMn spin valve read head biased for playback symmetry and magnetic stability

摘要

A spin valve sensor of a read head has a platinum manganese (PtMn) pinning layer that pins a magnetic moment of an antiparallel (AP) pinned layer structure. The pinned layer structure has a first AP pinned layer exchange coupled to the pinning layer so that the magnetic moment of the first AP pinned layer is pinned in a first direction and has a second AP pinned layer that has a magnetic moment pinned in a second direction antiparallel to the first direction. A free layer structure of the spin valve sensor is located asymmetrically between first and second shield layers so that when a sense current is conducted through the sensor a net image current field is executed on the free layer structure by the shield layers. One of the AP layers is thicker than the other so that H_I=H_FC+H_D+H_IM is exerted on the free layer structure where H_I is a sense current field from all conductive layers other than the free layer structure, H_FC is a ferromagnetic coupling field from the second AP pinned layer, H_D is a net demagnetization field from the AP pinned layer structure and H_IM is a net image current field from the shield layers.