Method and apparatus for a current-perpendicular-to-plane Giant Magneto-Resistance sensor with embedded composite film
View Patent ↗A Current-Perpendicular-to-Plane (CPP) Giant Magneto-Resistance (GMR) sensor ( 700/800 ) has either a composite film ( 708 ) embedded into a ferromagnetic reference layer ( 710 ) or a composite film ( 806 ) embedded into a ferromagnetic keeper layer ( 804 ). The embedded composite film is deposited by sputtering from a ferromagnetic metallic target and a non-magnetic oxide target simultaneously or sequentially. Varying sputtering powers of the ferromagnetic metallic and non-magnetic oxide targets leads to various volume fractions of ferromagnetic metallic and non-magnetic oxide phases. By carefully adjusting these volume fractions, the product of junction resistance and area of the CPP GMR sensor ( 700/800 ) can be finely tuned to a designed value and thus provide optimum read performance of the CPP GMR sensor ( 700/800 ) for magnetic recording at ultrahigh densities.
1. A Current-Perpendicular-to-Plane (CPP) Giant Magneto-Resistance (GMR) sensor comprising:
a ferromagnetic keeper layer having a first magnetic orientation;
a ferromagnetic reference layer having a second magnetic orientation anti-parallel to the first magnetic orientation;
a ferromagnetic sense layer having a magnetic orientation that varies in response to an external magnetic field;
a cap layer formed over and in contact with the ferromagnetic sense layer; and
a composite film, disposed between other layers forming the ferromagnetic keeper layer or the ferromagnetic reference layer, the composite film comprising:
a ferromagnetic metal having a first predetermined volume fraction of the composite film for providing a conducting phase; and
a non-magnetic oxide having a second predetermined volume fraction of the composite film for providing an insulating phase;
wherein a sense current is confined to flow only though the ferromagnetic metal of the composite film and the first and second predetermined volume fractions are selected to provide a predetermined junction resistance and area.
2. The CPP GMR sensor according to claim 1 , wherein the non-magnetic oxide is formed with a lower volume fraction than the ferromagnetic metal.
3. The CPP GMR sensor according to claim 1 , wherein the non-magnetic oxide is formed with a higher volume fraction than the ferromagnetic metal.
4. The CPP GMR sensor according to claim 1 , further comprising:
an anti-parallel pinning layer formed between the ferromagnetic keeper and reference layers; and
a conducting spacer layer formed between the ferromagnetic sense and reference layers.
5. The CPP GMR sensor according to claim 1 , wherein the composite film is embedded into the ferromagnetic keeper layer.
6. The CPP GMR sensor according to claim 1 , wherein the composite film is embedded into the ferromagnetic reference layer.
7. A magnetic storage system, comprising:
a magnetic recording medium;
a Current-Perpendicular-to-Plane (CPP) Giant Magneto-Resistance (GMR) sensor disposed proximate to the recording medium, the CPP GMR sensor including:
a ferromagnetic keeper layer having a first magnetic orientation;
a ferromagnetic reference layer having a second magnetic orientation anti-parallel to the first magnetic orientation;
a ferromagnetic sense layer having a magnetic orientation that varies in response to an external magnetic field;
a cap layer formed over and in contact with the ferromagnetic sense layer; and
a composite film, disposed within the ferromagnetic keeper layer or the ferromagnetic reference layer, the composite film comprising:
a ferromagnetic metal having a first predetermined volume fraction of the composite film for providing a conducting phase; and
a non-magnetic oxide having a second predetermined volume fraction of the composite film for providing an insulating phase;
wherein a sense current is confined to flow only though the ferromagnetic metal of the composite film and the first and second predetermined volume fractions are selected to provide a predetermined junction resistance and area.
8. The magnetic storage system according to claim 7 , wherein the magnetic oxide is formed with a lower volume fraction than the ferromagnetic metal.
9. The magnetic storage system according to claim 7 , wherein the magnetic oxide is formed with a higher volume fraction than the ferromagnetic metal.
10. The magnetic storage system according to claim 7 , further comprising:
an anti-parallel pinning layer formed between the ferromagnetic keeper and reference layers; and
a conducting spacer layer formed between the ferromagnetic sense and reference layers.
11. The magnetic storage system according to claim 7 , wherein the composite film is embedded into the ferromagnetic keeper layer.
12. The magnetic storage system according to claim 7 , wherein the composite film is embedded into the ferromagnetic reference layer.