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 boron-free ferromagnetic CoCr alloy that does not require a nucleation layer between it and the Cr alloy underlayer.

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 a magnetic recording layer that includes a ferromagnetic host layer and a ferromagnetic overlay deposited directly on the host layer with an effective overlay thickness in the range of 1-40 Angstroms. The ferromagnetic material used in the overlay contains Co, Fe and/or Ni and has a magnetic moment significantly greater than that of the material in the ferromagnetic host layer. The ferromagnetic overlays improve the thermal stability of superparamagnetic grains contained within the host layers by magnetically coupling the grains through bridging. The enhanced thermal stability of the media allows for the use of thinner ferromagnetic host layers, and leads to lower remanent magnetization-thickness product (Mrt) values and higher recording densities.

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 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 disk is patterned into discrete magnetic and nonmagnetic regions with the magnetic regions serving as the magnetic recording data bits. The magnetic recording layer comprises two ferromagnetic films separated by a nonferromagnetic spacer film. The spacer film material composition and thickness is selected such that the first and second ferromagnetic films are antiferromagnetically coupled across the spacer film. After this magnetic recording layer has been formed on the disk substrate, ions are irradiated onto it through a patterned mask. The ions disrupt the spacer film and thereby destroy the antiferromagnetic coupling between the two ferromagnetic films. As a result, in the regions of the magnetic recording layer that are ion-irradiated the first and second ferromagnetic films are essentially ferromagnetically coupled so that the magnetic moments from the ferromagnetic films are parallel and produce a magnetic moment that is essentially the sum of the moments from the two films.

Abstract: A patterned magnetic recording disk has a magnetic recording layer patterned into discrete magnetic and nonmagnetic regions having substantially the same chemical composition. The nonmagnetic regions have a chemically-ordered L12 crystalline structure and the magnetic regions have a chemically-disordered crystalline structure. The chemically-ordered intermetallic compound FePt3, which is nonferromagnetic, is rendered ferromagnetic by ion irradiation. This FePt3 material can be patterned by irradiating local regions through a mask to create magnetic regions that serve as the magnetic bits. The ions pass through the openings in the mask and impact the chemically-ordered FePt3 in selected regions corresponding to the pattern of holes in the mask. The ions disrupt the ordering of the Fe and Pt atoms in the unit cell and transform the FePt3 into magnetic regions corresponding to the mask pattern, with the regions of the film not impacted by the ions retaining their chemically-ordered structure.

Abstract: A magnetic recording disk has a magnetic recording layer formed on a special multilayered “host” layer. The host layer is a “synthetic antiferromagnetically”, i.e., at least two ferromagnetic films that are exchange-coupled antiferromagnetically (AF) to one another across a nonferromagnetic spacer film so that their magnetic moments are oriented antiparallel. The magnetic recording layer has a different composition from the top ferromagnetic film in the host layer and is ferromagnetically coupled to the top ferromagnetic film of the host layer. The magnetic volume V of the composite structure (magnetic recording layer and host layer) that determines the thermal stability will be approximately the sum of the volumes of the grains in the magnetic recording layer and the AF-coupled ferromagnetic films of the host layer.

Abstract: A patterned magnetic recording disk has a magnetic recording layer patterned into discrete magnetic and nonmagnetic regions having substantially the same chemical composition. The magnetic regions have a chemically-ordered L12 crystalline structure and the nonmagnetic regions have a chemically-disordered crystalline structure. The chemically-ordered intermetallic compound CrPt3, which is ferromagnetic, is rendered paramagnetic by ion irradiation. This CrPt3 material is patterned by irradiating local regions through a mask to create nonmagnetic regions. The ions pass through the openings in the mask and impact the chemically-ordered CrPt3 in selected regions corresponding to the pattern of holes in the mask. The ions disrupt the ordering of the Cr and Pt atoms in the unit cell and transform the CrPt3 into paramagnetic regions corresponding to the mask pattern, with the regions of the film not impacted by the ions retaining their chemically-ordered structure.

Abstract: A laminated magnetic recording medium for data storage uses a magnetic recording layer having at least two antiferromagnetically-coupled (AFC) layers spaced apart by a nonferromagnetic spacer layer. Each 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 of the second film to the first film. The magnetic moments of the two antiferromagnetically-coupled films in each AFC layer are oriented antiparallel, and thus the net remanent magnetization-thickness product (Mrt) of each AFC layer is the difference in the Mrt values of the two ferromagnetic films. The nonferromagnetic spacer layer between neighboring AFC layers has a composition and thickness to prevent any antiferromagnetic coupling of the ferromagnetic films of one AFC layer with the ferromagnetic films of the neighboring AFC layer.

Abstract: A magnetic recording medium for data storage uses a magnetic recording layer having at least two ferromagnetic films antiferromagnetically coupled together across a nonferromagnetic spacer film. The magnetic moments of the two antiferromagnetically-coupled films are oriented antiparallel, 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. This reduction in Mrt is accomplished without a reduction in the thermal stability of the recording medium because the volumes of the grains in the antiferromagnetically-coupled films add constructively. In a magnetic recording rigid disk application, the magnetic layer comprises two ferromagnetic films, each a granular film of a sputter deposited CoPtCrB alloy, separated by a Ru spacer film having a thickness to maximize the antiferromagnetic exchange coupling between the two CoPtCrB films.

Abstract: A magnetic recording medium for data storage uses a magnetic recording layer having at least two ferromagnetic films antiferromagnetically coupled together across a nonferromagnetic spacer film. The magnetic moments of the two antiferromagnetically-coupled films are oriented antiparallel, 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. This reduction in Mrt is accomplished without a reduction in the thermal stability of the recording medium because the volumes of the grains in the antiferromagnetically-coupled films add constructively. In a magnetic recording rigid disk application, the magnetic layer comprises two ferromagnetic films, each a granular film of a sputter deposited CoPtCrB alloy, separated by a Ru spacer film having a thickness to maximize the antiferromagnetic exchange coupling between the two CoPtCrB films.