Abstract: A magnetoresistive sensor having a hard magnetic pinning layer with an engineered magnetic anisotropy in a direction substantially perpendicular to the medium facing surface. The hard magnetic pinning layer may be constructed of CoPt, CoPtCr, or some other magnetic material and is deposited over an underlayer that has been ion beam etched. The ion beam etch has been performed at an angle with respect to normal in order to induce anisotropic roughness for example in form of oriented ripples or facets oriented along a direction parallel to the medium facing surface. The anisotropic roughness induces a strong uniaxial magnetic anisotropy substantially perpendicular to the medium facing surface in the hard magnetic pinning layer deposited there over.

Abstract: A magnetoresistive sensor having an in stack bias layer with an engineered magnetic anisotropy in a direction parallel with the medium facing surface. The in-stack bias layer may be constructed of CoPt, CoPtCr or some other magnetic material and is deposited over an underlayer that has been ion beam etched. The ion beam etch has been performed at an angle with respect to normal in order to form anisotropic roughness in form of oriented ripples or facets. The anisotropic roughness induces a uniaxial magnetic anisotropy substantially parallel to the medium facing surface in the hard magnetic in-stack bias layer deposited thereover.

Abstract: A laminated magnetic recording structure for use in perpendicular or longitudinal recording is described. A small amount of ferromagnetic coupling is added between the two magnetic layers that are sufficiently decoupled to switch independently. In one embodiment the coupling is achieved by doping the spacer layer with a ferromagnetic material. Ruthenium (Ru), which is a preferred nonmagnetic material for spacer layers with cobalt (Co) being the preferred magnetic material. The weak ferromagnetic coupling can also be achieved through the use of platinum, palladium and alloys thereof for the spacer layer without the addition of a ferromagnetic element, but alternatively they can also be doped with ferromagnetic elements. For embodiments for perpendicular recording the spacer layer further can additionally comprise oxides of one or more elements selected from the group consisting of Si, Ta, Ti, Nb, Cr, V and B.

Abstract: A magnetic recording disk has an antiferromagnetically-coupled (AFC) structure that has three lower ferromagnetic layers (LL1, LL2, LL3) and an upper ferromagnetic layer (UL), all four ferromagnetic layers being antiferromagnetically-coupled together across corresponding antiferromagnetically-coupling layers. The UL has a magnetization-remanence-thickness product (Mrt) greater than the Mrt each of the three lower layers LL1, LL2, LL3, and greater than the sum of the Mrt values of LL1 and LL3. The middle lower layer LL2 has an Mrt less than the Mrt of each of the other lower layers LL1 and LL3, and as a result the composite Mrt of the AFC structure is less than the composite Mrt of a conventional AFC structure having only a single lower layer. The AFC structure achieves this composite Mrt reduction without increasing the Mrt of any of the three lower layers above the maximum Mrt of the single lower layer in the conventional AFC structure.

Abstract: An exchange-coupled magnetic structure includes a ferromagnetic layer, a coercive ferrite layer, such as cobalt-ferrite, for biasing the magnetization of the ferromagnetic layer, and an oxide underlayer, such as cobalt-oxide, in proximity to the coercive ferrite layer. The oxide underlayer has a lattice structure of either rock salt or a spinel and exhibits no magnetic moment at room temperature. The underlayer affects the structure of the coercive ferrite layer and therefore its magnetic properties, providing increased coercivity and enhanced thermal stability. As a result, the coercive ferrite layer is thermally stable at much smaller thicknesses than without the underlayer. The exchange-coupled structure is used in spin valve and magnetic tunnel junction magnetoresistive sensors in read heads of magnetic disk drive systems. Because the coercive ferrite layer can be made as thin as 1 nm while remaining thermally stable, the sensor satisfies the narrow gap requirements of high recording density systems.

Abstract: A magnetic recording disk has an antiferromagnetically-coupled (AFC) structure that has an upper ferromagnetic layer (UL), and a lower ferromagnetic layer structure formed of two ferromagnetically-coupled lower layers (LL1, LL2). The UL is antiferromagnetically-coupled to the lower layer structure across an antiferromagnetically-coupling layer. LL1 and LL2 are ferromagnetically coupled across a ferromagnetic coupling layer so the magnetizations of LL1 and LL2 remain parallel in each remanent magnetic state, but are antiparallel to the magnetization of the UL in each remanent magnetic state. The UL has an Mrt greater than the sum of the Mrt values of LL1 and LL2.

Abstract: An exchange-coupled magnetic structure includes a ferromagnetic layer, a coercive ferrite layer, such as cobalt-ferrite, for biasing the magnetization of the ferromagnetic layer, and an oxide underlayer, such as cobalt-oxide, in proximity to the coercive ferrite layer. The oxide underlayer has a lattice structure of either rock salt or a spinel and exhibits no magnetic moment at room temperature. The underlayer affects the structure of the coercive ferrite layer and therefore its magnetic properties, providing increased coercivity and enhanced thermal stability. As a result, the coercive ferrite layer is thermally stable at much smaller thicknesses than without the underlayer. The exchange-coupled structure is used in spin valve and magnetic tunnel junction magnetoresistive sensors in read heads of magnetic disk drive systems. Because the coercive ferrite layer can be made as thin as 1 nm while remaining thermally stable, the sensor satisfies the narrow gap requirements of high recording density systems.

Abstract: The invention is a magnetic device, i.e., a magnetoresistive sensor or a magnetic tunnel junction device, that has a ferromagnetic structure of two ferromagnetic layers antiferromagnetically coupling together with an improved antiferromagnetically coupling (AFC) film. The AFC film is an alloy of Ru100-xFex where x is between approximately 10 and 60 atomic percent. This AFC film increases the exchange coupling by up to a factor or two and has an hcp crystalline structure making it compatible with Co alloy ferromagnetic layers.

Abstract: A magnetic recording disk has a ferromagnetic structure of two ferromagnetic layers antiferromagnetically coupled together with an improved antiferromagnetically coupling (AFC) film. The AFC film is an alloy of Ru100-xFex where x is between approximately 10 and 60 atomic percent. This AFC film increases the exchange coupling by up to a factor or two and has an hcp crystalline structure making it compatible with Co alloy ferromagnetic layers.

Abstract: The invention is a magnetic device, i.e., a magnetoresistive sensor or a magnetic tunnel junction device, that has a ferromagnetic structure of two ferromagnetic layers antiferromagnetically coupled together with an improved antiferromagnetically coupling (AFC) film. The AFC film is an alloy of Ru100-xFex where x is between approximately 10 and 60 atomic percent. This AFC film increases the exchange coupling by up to a factor or two and has an hcp crystalline structure making it compatible with Co alloy ferromagnetic layers.

Abstract: An exchange-coupled magnetic structure includes a ferromagnetic layer, a coercive ferrite layer, such as cobalt-ferrite, for biasing the magnetization of the ferromagnetic layer, and an oxide underlayer, such as cobalt-oxide, in proximity to the coercive ferrite layer. The oxide underlayer has a lattice structure of either rock salt or a spinel and exhibits no magnetic moment at room temperature. The underlayer affects the structure of the coercive ferrite layer and therefore its magnetic properties, providing increased coercivity and enhanced thermal stability. As a result, the coercive ferrite layer is thermally stable at much smaller thicknesses than without the underlayer. The exchange-coupled structure is used in spin valve and magnetic tunnel junction magnetoresistive sensors in read heads of magnetic disk drive systems. Because the coercive ferrite layer can be made as thin as 1 nm while remaining thermally stable, the sensor satisfies the narrow gap requirements of high recording density systems.

Abstract: A magnetic recording medium for data storage uses a magnetic recording layer having at least two ferromagnetic films exchange coupled together antiferromagnetically across a nonferromagnetic spacer film. In this antiferromagnetically-coupled (AFC) recording layer the magnetic moments of the two ferromagnetic films are oriented antiparallel, and thus the net remanent magnetization-thickness product (Mrt) of the AFC recording layer is the difference in the Mrt values of the two ferromagnetic films. This reduction in Mrt is accomplished without a reduction in thermal stability of the recording medium. The lower ferromagnetic film in the AFC recording layer is a ferromagnetic CoCrFe alloy that does not require a nucleation layer between it and the Cr alloy underlayer. The medium with the CoCrFe alloy as the first or lower ferromagnetic film in the AFC recording layer has reduced intrinsic media noise.

Abstract: A magnetic recording medium for data storage uses a magnetic recording layer having at least two ferromagnetic films exchange coupled together antiferromagnetically across a nonferromagnetic spacer film. In this antiferromagnetically-coupled (AFC) recording layer the magnetic moments of the two ferromagnetic films are oriented antiparallel, and thus the net remanent magnetization-thickness product (Mrt) of the AFC recording layer is the difference in the Mrt values of the two ferromagnetic films. This reduction in Mrt is accomplished without a reduction in thermal stability of the recording medium. The lower ferromagnetic film in the AFC recording layer is a ferromagnetic CoCrFe alloy that does not require a nucleation layer between it and the Cr alloy underlayer. The medium with the CoCrFe alloy as the first or lower ferromagnetic film in the AFC recording layer has reduced intrinsic media noise.

Abstract: A magnetic recording disk has a ferromagnetic recording layer and a “paramagnetic” write assist layer in contact and exchange coupled with the ferromagnetic recording layer. The write assist layer is a ferromagnetic material that has a Curie temperature less than the operating temperature of the disk drive so that at operating temperature and in the absence of a write field, the write assist layer is in its paramagnetic state and has no remanent magnetization. When a write field is applied in a direction opposite to the magnetization in previously written regions of the ferromagnetic recording layer, the write assist layer exhibits a magnetization aligned with the write field and assists the write field in reversing the magnetization in the ferromagnetic recording layer due to the exchange coupling.

Abstract: A laminated magnetic recording medium for data storage has an antiferromagnetically-coupled (AFC) layer and a single ferromagnetic layer spaced apart by a nonferromagnetic spacer layer. The AFC layer is formed as two ferromagnetic films antiferromagnetically coupled together across an antiferromagnetically coupling film that has a composition and thickness to induce antiferromagnetic coupling. In each of the two remanent magnetic states, the magnetic moments of the two antiferromagnetically-coupled films in the AFC layer are oriented antiparallel, and the magnetic moment of the single ferromagnetic layer and the greater-moment ferromagnetic film of the AFC layer are oriented parallel. The nonferromagnetic spacer layer between the AFC layer and the single ferromagnetic layer has a composition and thickness to prevent antiferromagnetic exchange coupling. The laminated medium has improved thermal stability and reduced intrinsic media noise.

Abstract: A magnetic recording medium for data storage uses a magnetic recording layer having at least two ferromagnetic films with different remanent magnetization-thickness (Mrt) values that are coupled antiparallel across a nonferromagnetic spacer film predominantly by the dipole field (Hd) from the grains of the higher-Mrt ferromagnetic film. The material compositions and thicknesses of the ferromagnetic films and the nonferromagnetic spacer film are selected so that Hd predominates over any antiferromagnetic exchange coupling field (Haf) and is greater than the coercive field of the lower-Mrt ferromagnetic film. As a result, the magnetizations of the two ferromagnetic films are antiparallel in the two remanent magnetic states, and thus the net remanent magnetization-thickness product (Mrt) of the recording layer is the difference in the Mrt values of the two ferromagnetic films.

Abstract: The invention is a magnetic device that includes a ferromagnetic/antiferromagnetic (F/AF) structure wherein the ferromagnetic layer is perpendicularly exchange biased by the antiferromagnetic layer. The invention has application to perpendicular magnetic recording disks and magnetic tunnel junction devices used as read heads for disk drives and memory cells in magnetic memory arrays.

Abstract: The invention is a magnetic device that includes a ferromagnetic/antiferromagnetic (F/AF) structure wherein the ferromagnetic layer is perpendicularly exchange biased by the antiferromagnetic layer. The invention has application to perpendicular magnetic recording disks and magnetic tunnel junction devices used as read heads for disk drives and memory cells in magnetic memory arrays.

Abstract: A magnetic recording medium for data storage uses a magnetic recording layer having at least two ferromagnetic films with different remanent magnetization-thickness (Mrt) values that are coupled antiparallel across a nonferromagnetic spacer film predominantly by the dipole field (Hd) from the grains of the higher-Mrt ferromagnetic film. The material compositions and thicknesses of the ferromagnetic films and the nonferromagnetic spacer film are selected so that Hd predominates over any antiferromagnetic exchange coupling field (Haf) and is greater than the coercive field of the lower-Mrt ferromagnetic film. As a result, the magnetizations of the two ferromagnetic films are antiparallel in the two remanent magnetic states, and thus the net remanent magnetization-thickness product (Mrt) of the recording layer is the difference in the Mrt values of the two ferromagnetic films.

Abstract: A method for writing data on a magnetic recording medium includes providing a magnetic recording layer having at least two ferromagnetic films antiferromagnetically coupled together across a nonferromagnetic spacer film, with one of the ferromagnetic films having a greater magnetic moment than the other. A positive write field is applied to a first region to align the moments of both ferromagnetic films with the positive field, and then a negative write field is applied to an adjacent region to align the moments of both ferromagnetic films with the negative field. When the medium is moved away from the write fields, the moment of the ferromagnetic film with the lesser moment in each region flips to be antiparallel to the moment of the other ferromagnetic film in its region. The result is that the adjacent regions become adjacent magnetized domains with the transition between the domains representative of the written data.