AP pinned spin valve read head with a negative ferromagnetic field biased for zero asymmetry

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. For example, if the second AP pinned layer is thicker than the first AP pinned layer 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 negative 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.