CURRENT-PERPENDICULAR-TO-PLANE (CPP) READ SENSOR WITH Co-Fe BUFFER LAYERS

A read sensor, comprising:

• a non-magnetic barrier or spacer layer sandwiched between upper and lower sensor stacks, the upper sensor stack comprising a magnetic sense layer structure, the lower sensor stack comprising a pinning layer, a keeper layer structure formed on the pinning layer, a non-magnetic antiparallel coupling layer formed on the keeper layer and a reference layer structure formed on the non-magnetic antiparallel coupling layer, wherein:
• the keeper layer structure comprises a Co—Fe buffer layer adjacent to the pinning layer, a second Co—Fe buffer layer adjacent to the non-magnetic antiparallel coupling layer and an intermediate layer comprising Co—Hf or Co—Fe—B sandwiched between the first and second Co—Fe buffer layers;
• and
• the reference layer structure comprises:
• a third Co—Fe buffer layer adjacent to the non-magnetic antiparallel coupling layer;
• a first intermediate reference layer comprising a Co—Hf film formed on the third buffer layer;
• a second intermediate reference layer comprising Co—Fe—B formed on the first intermediate reference layer, and
• a fourth Co—Fe buffer layer formed of a ferromagnetic Co—Fe—B film formed on the second intermediate reference layer.