Magnetoresistance effect element, magnetic head, magnetic head assembly, magnetic storage system

A magnetic storage system, comprising:

• a recording/reproducing magnetic head including a substrate, a lower magnetic shield layer formed on a main surface of the substrate, and a magnetoresistance effect element formed on the lower magnetic shield layer,
• wherein the magnetoresistance effect element includes, a nonmagnetic spacer layer;
• first and second ferromagnetic layers separated by the nonmagnetic spacer layer, the first ferromagnetic layer having a magnetization direction at an angle relative to a magnetization direction of the second ferromagnetic layer at zero applied magnetic field, the second ferromagnetic layer comprising first and second ferromagnetic films antiferromagnetically coupled to one another and an antiferromagnetically coupling film located between and in contact with the first and second ferromagnetic films for coupling the first and second ferromagnetic films together antiferromagnetically so that their magnetizations are aligned antiparallel with one another and remain antiparallel in the presence of an applied magnetic field, the magnetization of the first ferromagnetic layer freely rotating in a magnetic field signal;
• and
• a nonmagnetic conductivity layer disposed in contact with the first ferromagnetic layer so that the first ferromagnetic layer is disposed between the nonmagnetic conductivity layer and the nonmagnetic spacer layer,
• wherein the first ferromagnetic layer has a film thickness between 0.5 nanometers and 4.5 nanometers, and
• the nonmagnetic spacer layer, the first ferromagnetic layer, and the second ferromagnetic layer have a film thickness so that a bias point B.P. is in the range of 30–50% when a product of a magnetic saturation Ms and a thickness t of the first ferromagnetic layer is between 2 and 3 m·T, in which,
• B.P.=50×(Hshift/Hs)+50, and
• Hshift=−Hin+Hpin±Hcu,
• Hshift is the sum of magnetic fields applied to the first ferromagnetic layer,
• Hs is an inclination of a transfer curve, Hin is a coupling magnetic field of the first and second ferromagnetic layers via the nonmagnetic spacer layer,
• Hpin is a stray magnetic field from the second ferromagnetic layer to the first ferromagnetic layer, and
• Hcu is a magnetic field to be applied to the first ferromagnetic layer.

A magnetoresistance effect element, comprising:

• a nonmagnetic spacer layer,
• first and second ferromagnetic layers separated by the nonmagnetic spacer layer, the first ferromagnetic layer having a magnetization direction at an angle relative to a magnetization direction of the second ferromagnetic layer at zero applied magnetic field, the second ferromagnetic layer comprising first and second ferromagnetic films antiferromagnetically coupled to one another and an antiferromagnetically coupling film located between and in contact with the first and second ferromagnetic films for coupling the first and second ferromagnetic films together antiferromagnetically so that their magnetizations are aligned antiparallel with one another and remain antiparallel in the presence of an applied magnetic field, the magnetization of the first ferromagnetic layer freely rotatable in a magnetic field signal, and
• a nonmagnetic conductivity layer disposed in contact with the first ferromagnetic layer so that the first ferromagnetic layer is disposed between the nonmagnetic conductivity layer and the nonmagnetic spacer layer, wherein:
• the first ferromagnetic layer has a film thickness between 0.5 nanometers and 4.5 nanometers, and
• the nonmagnetic spacer layer, the first ferromagnetic layer, and the second ferromagnetic layer have a film thickness so that a bias point B.P. is in the range of 30–50% when a product of a magnetic saturation Ms and a thickness t of the first ferromagnetic layer is between 2 and 3 nm·T, in which,
• B.P.=50×(Hshift/Hs)+50, and
• Hshift=−Hin+Hpin±Hcu,
• Hshift is the sum of magnetic fields applied to the first ferromagnetic layer,
• Hs is an inclination of a transfer curve, Hin is a coupling magnetic field of the first and second ferromagnetic layers via the nonmagnetic spacer layer,
• Hpin is a stray magnetic field from the second ferromagnetic layer to the first ferromagnetic layer, and
• Hcu is a magnetic field to be applied to the first ferromagnetic layer.

A magnetic head assembly comprising:

• a head slider that comprises a magnetoresistance effect head including:
• a nonmagnetic spacer layer,
• first and second ferromagnetic layers separated by the nonmagnetic spacer layer, the first ferromagnetic layer having a magnetization direction at an angle relative to a magnetization direction of the second ferromagnetic layer at zero applied magnetic field, the second ferromagnetic layer comprising first and second ferromagnetic films antiferromagnetically coupled to one another and an antiferromagnetically coupling film located between and in contact with the first and second ferromagnetic films for coupling the first and second ferromagnetic films together antiferromagnetically so that their magnetizations are aligned antiparallel with one another and remain antiparallel in the presence of an applied magnetic field, the magnetization of the first ferromagnetic layer freely rotating in a magnetic field signal, and
• a nonmagnetic high-conductivity layer disposed in contact with the first ferromagnetic layer so that the first ferromagnetic layer is disposed between the nonmagnetic conductivity layer and the nonmagnetic spacer layer, and
• a suspension arm holding the magnetoresistance effect head, wherein:
• the first ferromagnetic layer has a film thickness between 0.5 nanometers and 4.5 nanometers, and
• the nonmagnetic spacer layer, the first ferromagnetic layer, and the second ferromagnetic layer have a film thickness so that a bias point B.P. is in the range of 30–50% when a product of a magnetic saturation Ms and a thickness t of the first ferromagnetic layer is between 2 and 3 nm·T, in which,
• B.P.=50×(Hshift/Hs)+50, and
• Hshift=−Hin+Hpin±Hcu,
• Hshift is the sum of magnetic fields applied to the first ferromagnetic layer,
• Hs is an inclination of a transfer curve, Hin is a coupling magnetic field of the first and second ferromagnetic layers via the nonmagnetic spacer layer,
• Hpin is a stray magnetic field from the second ferromagnetic layer to the first ferromagnetic layer, and
• Hcu is a magnetic field to be applied to the first ferromagnetic layer.

A magnetic recording apparatus comprising:

• a magnetic medium,
• a magnetic head assembly that comprises:
• a head slider including a magnetoresistance effect head having:
• a nonmagnetic spacer layer,
• first and second ferromagnetic layers separated by the nonmagnetic spacer layer, the first ferromagnetic layer having a magnetization direction at an angle relative to a magnetization direction of the second ferromagnetic layer at zero applied magnetic field, the second ferromagnetic layer comprising first and second ferromagnetic films antiferromagnetically coupled to one another and an antiferromagnetically coupling film located between and in contact with the first and second ferromagnetic films for coupling the first and second ferromagnetic films together antiferromagnetically so that their magnetizations are aligned antiparallel with one another and remain antiparallel in the presence of an applied magnetic field, the magnetization of the first ferromagnetic layer freely rotating in a magnetic field signal, and
• a nonmagnetic high-conductivity layer disposed in contact with the first ferromagnetic layer so that the first ferromagnetic layer is disposed between the nonmagnetic conductivity layer and the nonmagnetic spacer layer, and
• a suspension arm holding the magnetoresistance effect head, wherein:
• the first ferromagnetic layer has a film thickness between 0.5 nanometers and 4.5 nanometers, and
• the nonmagnetic spacer layer, the first ferromagnetic layer, and the second ferromagnetic layer have a film thickness so that a bias point B.P. is in the range of 30–50% when a product of a magnetic saturation Ms and a thickness t of the first ferromagnetic layer is between 2 and 3 nm·T, in which,
• B.P.=50×(Hshift/Hs)+50, and
• Hshift=−Hin+Hpin±Hcu,
• Hshift is the sum of magnetic fields applied to the first ferromagnetic layer,
• Hs is an inclination of a transfer curve, Hin is a coupling magnetic field of the first and second ferromagnetic layers via the nonmagnetic spacer layer,
• Hpin is a stray magnetic field from the second ferromagnetic layer to the first ferromagnetic layer, and
• Hcu is a magnetic field to be applied to the first ferromagnetic layer.