Enhanced spin-valve sensor with engineered overlayer formed on a free layer
AssigneeHitachi Global Storage Technologies Netherlands B.V.
InventorsWitold Kula, Alexander M. Zeltser
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Abstract
A GMR sensor is disclosed for sensing magnetically recorded information on a data storage medium. The sensor includes a ferromagnetic free layer and a ferromagnetic pinned layer sandwiching an electrically conductive spacer layer. An engineered overlayer is formed on the free layer to decrease free layer magnetic thickness without reducing physical thickness.
Claims27
A magnetic disk drive having a housing, a magnetic disk rotatably supported in the housing, a rotary actuator adapted to position a transducer-carrying slider above a recording surface of the magnetic disk, and a GMR sensor with reduced free layer magnetic thickness without reduced free layer physical thickness formed as part of the transducer, the sensor being adapted to sense magnetically recorded information on the recording surface, and comprising:
- a ferromagnetic free layer having a substantially free magnetic moment, a physical thickness (t) and a magnetic thickness (Mr*t) representing the product of a remanent magnetic moment density (Mr) of said free layer and said free layer physical thickness (t);
- a ferromagnetic pinned layer having a substantially fixed magnetic moment oriented generally perpendicular to said free layer magnetic moment;
- a nonmagnetic electrically conductive spacer layer sandwiched between said pinned layer and said free layer;
- a protective electrically non-conducting overlayer directly on and contacting said free layer, said overlayer being adapted to reduce free layer magnetic thickness to a desired level without reducing free layer physical thickness;
- and
- said free layer having negative magnetostriction in a range of approximately −2×10−6 to less than zero.
A magnetic head having a GMR read sensor with reduced free layer magnetic thickness without reduced free layer physical thickness, said sensor being situated between a pair of electrical leads for delivering a sense current through the sensor, the sensor comprising:
- a ferromagnetic free layer having a substantially free magnetic moment, a physical thickness (t) and a magnetic thickness (Mr*t) representing the product of a remanent magnetic moment density (Mr) of said free layer and said free layer physical thickness (t);
- a ferromagnetic pinned layer having a substantially fixed magnetic moment oriented generally perpendicular to said free layer magnetic moment;
- a nonmagnetic electrically conductive spacer layer sandwiched between said pinned layer and said free layer;
- a protective electrically non-conducting overlayer directly on and contacting said free layer, said overlayer being adapted to reduce free layer magnetic thickness to a desired level without reducing free layer physical thickness;
- and
- said free layer having negative magnetostriction in a range of approximately −2×10−6 to less than zero.
A GMR sensor with reduced free layer magnetic thickness without reduced free layer physical thickness, comprising:
- a ferromagnetic free layer having a substantially free magnetic moment, a physical thickness (t) and a magnetic thickness (Mr*t) representing the product of a remanent magnetic moment density (Mr) of said free layer and said free layer physical thickness (t);
- a ferromagnetic pinned layer having a substantially fixed magnetic moment oriented generally perpendicular to said free layer magnetic moment;
- a nonmagnetic electrically conductive spacer layer sandwiched between said pinned layer and said free layer;
- a protective electrically non-conducting overlayer directly on and contacting said free layer, said overlayer being adapted to reduce free layer magnetic thickness to a desired level without reducing free layer physical thickness;
- and
- said free layer having negative magnetostriction in a range of approximately −2×10−6 to less than zero.
Dependencies are inferred from the claim text.