Current-perpendicular-to-the-plane (CPP) magnetoresistive sensor with antiparallel-pinned layer containing silicon

A current-perpendicular-to-the-plane magnetoresistive read head for reading magnetically recorded data from tracks on a magnetic recording medium, the head comprising:

• a first shield layer of magnetically permeable material;
• a seed layer on the first shield;
• an antiparallel (AP) pinned structure on the seed layer and comprising a first AP-pinned (AP1) ferromagnetic layer on the seed layer and having an in-plane magnetization direction, a second AP-pinned (AP2) ferromagnetic layer having an in-plane magnetization direction substantially antiparallel to the magnetization direction of the AP1 layer, the AP2 layer being a multilayer comprising a first AP2-1 sublayer and a second AP2-2 sublayer, and an AP coupling (APC) layer between and in contact with the AP1 layer and the first AP2-1 sublayer;
• a spacer layer on the second AP2-2 sublayer;
• a free ferromagnetic layer on the spacer layer and having an in-plane magnetization direction oriented substantially orthogonal to the magnetization directions of the AP1 and AP2 layers in the absence of an external magnetic field;
• wherein each of the free ferromagnetic layer and the second AP2-2 sublayer comprises a ferromagnetic alloy consisting essentially of only Co, Fe and Si according to the formula (CoxFe(100-x))(100-y)Siy, where the subscripts represent atomic percent, x is between 45 and 55, and y is between 20 and 30, and wherein the first AP2-1 sublayer in contact with the APC layer contains no Si;
• a capping layer on the free ferromagnetic layer;
• and
• a second shield layer of magnetically permeable material on the capping layer.