Magnetoresistive sensor with antiparallel coupled lead/sensor overlap region
View Patent ↗A spin valve sensor with an antiparallel coupled lead/sensor overlap region is provided comprising a ferromagnetic bias layer antiparallel coupled to a free layer in first and second passive regions where first and second lead layers overlap the spin valve sensor layers. The ferromagnetic material of the bias layer in a track width region defined by a space between the first and second lead layers is converted to a nonmagnetic oxide layer allowing the free layer in the track width region to rotate in response to signal fields from a magnetic disk.
1. A spin valve (SV) sensor having first and second passive regions and a central track width region transversely disposed between said first and second passive regions, said SV sensor comprising:
a pinned layer;
a ferromagnetic free layer;
a spacer layer sandwiched between said pinned layer and said free layer;
a ferromagnetic bias layer in said first and second passive regions;
a non magnetic oxide layer in said central track region transversely disposed between the ferromagnetic bias layer in the first and second passive regions;
an antiparallel coupled layer sandwiched between said free layer and said ferromagnetic bias layer for providing strong antiparallel coupling between said bias layer and said free layer in the first and second passive regions;
a first cap layer formed on said ferromagnetic bias layer; and
a second cap layer formed over said non magnetic oxide layer.
2. The SV sensor as recited in claim 1 wherein first and second lead layers connected to the spin valve sensor overlap the bias layer in the first and second passive regions, respectively.
3. The SV sensor as recited in claim 2 wherein the track width region between the first and second passive regions is defined by a space between the first and second lead layers.
4. The SV sensor as recited in claim 1 wherein the free layer comprises:
a second free sublayer, and
a first free sublayer sandwiched between the second free sublayer and the spacer layer.
5. The SV sensor as recited in claim 4 wherein the first free sublayer is made of Co—Fe and the second free sublayer is made of Ni—Fe.
6. The SV sensor as recited in claim 1 wherein the bias layer comprises:
a second bias sublayer; and
a first bias sublayer sandwiched between the second bias sublayer and the antiparallel coupling layer.
7. The SV sensor as recited in claim 6 wherein the first bias sublayer is made of Co—Fe and the second bias sublayer is made of Ni—Fe.
8. The SV sensor as recited in claim 1 wherein said first cap layer is made of Ta and Ru.
9. The SV sensor as recited in claim 1 wherein said second cap layer is chosen from a group of materials consisting of Rh and Ru.