CPP spin valve with long spin diffusion length AP1 layers
View Patent ↗A magnetoresistive sensor having a pinned layer that includes a first magnetic layer (AP1) a second magnetic layer (AP2) and an antiparallel coupling layer sandwiched between the AP1 and AP2 layers. The AP1 layer is adjacent to a layer of antiferromagnetic material (AFM layer) and is constructed so as to have a long spin diffusion length. The long spin diffusion length of the AP1 layer minimizes the negative GMR contribution of the AP1 layer, thereby increasing the overall GMR effect of the sensor.
1. A magnetoresistive sensor, comprising:
a pinned magnetic layer structure, having a first magnetic layer structure (AP1) a second magnetic layer structure (AP2) and a non-magnetic antiparallel coupling layer sandwiched between the (AP1) and (AP2) layers;
a free magnetic layer structure;
a non-magnetic layer sandwiched between the free layer and the pinned layer; and
a layer of antiferromagnetic material (AFM layer) adjacent to the AP1 layer of the pinned layer structure; wherein
the AP1 layer structure further comprises:
a layer of CoFe adjacent to the AFM layer; and
a layer of a metal consisting of a single element metal;
wherein the layer of pure, single element metal consists of Ni.
2. A magnetoresistive sensor, comprising:
a pinned magnetic layer structure, having a first magnetic layer structure (AP1) a second magnetic layer structure (AP2) and a non-magnetic antiparallel coupling layer sandwiched between the (AP1) and (AP2) layers;
a free magnetic layer structure;
a non-magnetic layer sandwiched between the free layer and the pinned layer; and
a layer of antiferromagnetic material (AFM layer) adjacent to the AP1 layer of the pinned layer structure; wherein
the AP1 layer structure further comprises:
a layer of CoFe adjacent to the AFM layer;
a first layer of single element metal adjacent to the layer of CoFe;
a thin layer of Ta; and
a second layer of single element metal, the thin layer of Ta being sandwiched between the first and second layer of single element metal.
3. A sensor as in claim 2 wherein the first and second layers of single element metal each consist of Co.
4. A sensor as in claim 2 wherein the first and second layers of single element metal each consist of Ni.
5. A sensor as in claim 2 wherein the thin layer of Ta has a thickness no greater than 4 Angstroms.
6. A sensor as in claim 2 wherein the thin layer of Ta has a thickness of about 12 Angstroms.
7. A sensor as in claim 2 wherein the thin layer of Ta has a thickness no greater than 12 Angstroms.
8. A sensor as in claim 2 wherein the layer of CoFe has 30-40 atomic percent Fe and has a thickness of 10-20 Angstroms.
9. A sensor as in claim 2 , wherein:
the layer of CoFe has 30-40 atomic percent Fe, and has a thickness of 10-20 Angstroms;
the first layer of single element metal consists of Co and has a thickness of 15-25 Angstroms;
the Ta layer has a thickness of about 4 Angstroms; and
the second layer of single element metal consists of Co and has a thickness of about 12 Angstroms.