摘要:
A magnetically-coupled structure has two ferromagnetic layers with their in-plane magnetization directions coupled orthogonally across an electrically-conducting spacer layer that induces the direct orthogonal magnetic coupling. The structure has application for in-stack biasing in a current-perpendicular-to-the-plane (CPP) magnetoresistive sensor. One of the ferromagnetic layers of the structure is a biasing ferromagnetic layer and the other ferromagnetic layer is the sensor free layer. An antiferromagnetic layer exchange-couples the biasing layer to fix its moment parallel to the moment of the sensor pinned layer. This allows a single annealing step to be used to set the magnetization direction of the biasing and pinned layers. The electrically-conducting spacer layer, the biasing layer and the antiferromagnetic layer that exchange-couples the biasing layer may all extend beyond the edges of the sensor stack.
摘要:
A magnetoresistive sensor having a self biased free layer. The free layer is constructed upon an underlayer that has been treated by a surface texturing process that configures the underlayer with an anisotropic roughness that induces a magnetic anisotropy in the free layer. The treated layer underlying the free layer can be a spacer layer sandwiched between the free layer and pinned layer or can be a separate underlayer formed opposite the spacer layer. Alternatively, the texturing of an underlayer can be used to induce a magnetic anisotropy in a bias layer that is separated from the free layer by an orthogonal coupling layer. This self biasing of the free layer induced by texturing can also be used in conjunction with biasing from a hard-bias structure.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
A magnetoresistive sensor having a magnetically stable free layer fabricated from a material having a positive magnetostriction such as a Co—Fe—B alloy. Although the free layer is fabricated from a material that has a positive magnetostriction, which would ordinarily make the free layer unstable, the magnetization of the free layer remains stable because of an induced magnetic anisotropy that has an easy axis of magnetization oriented parallel to the Air-bearing Surface (ABS). This magnetic anisotropy of the free layer is induced by an anisotropic texturing of the surface of the free layer. The resulting anisotropic surface texture is produced by an ion milling process that utilizes an ion beam directed at an acute angle relative to the normal to the surface of the wafer whereon the sensor is fabricated while the wafer is held on a stationary chuck. This angled, static ion milling produces an anisotropic surface texture, or roughness, of the free layer, which results in the above described magnetic anisotropy with an easy axis of magnetization in a desired orientation.
摘要:
A magnetic shield for use in a magnetic head. The magnetic shield has a magnetic anisotropy associated with a magnetic easy axis of magnetization oriented substantially parallel with the air bearing surface. The magnetic anisotropy of the shield is induced by an anisotropic surface texture. This anisotropic surface texture can be formed in a surface of one or more magnetic layers of the shield, or can be formed in a surface of an under-layer on which the shield is deposited. The shield could also be constructed as a lamination of magnetic layers separated by non-magnetic layers, with the anisotropic surface texture being formed on one or more of the non-magnetic layers.
摘要:
A magnetic write head for magnetic data recording. The magnetic write head has a write pole with a magnetic anisotropy induced by an angled, directional ion milling of a seed layer. The magnetic anisotropy is such that a magnetic easy axis of magnetization is oriented substantially parallel with the air bearing surface (ABS) of the write head. This orientation of the easy axis of magnetization increases the write speed and data rate of the write head by increasing the speed with which the magnetization of the write pole can switch from one direction to another writing.
摘要:
A method for manufacturing a magnetic layer with a magnetic anisotropy. The method includes an endpoint detection process for determining an end point to carefully control the final thickness of the magnetic layer. The method includes depositing a magnetic layer and then depositing a sacrificial layer over the magnetic layer. A low power angled ion milling is then performed until the magnetic layer has been reached. The angled ion milling can be performed at an angle relative to normal and without rotation in order to form an anisotropic surface texture that induces a magnetic anisotropy in the magnetic layer. An indicator layer may be included between the magnetic layer and the sacrificial layer in order to further improve endpoint detection.
摘要:
A Magnetic Random Access Memory (MRAM) cell and array for storing data. The MRAM array includes a memory cell having a magnetic pinned layer, a magnetic free layer and a non-magnetic spacer or barrier layer sandwiched between the pinned and free layer. The pinned layer has magnetization that is pinned, and the free layer has a magnetization that is free to rotate but is stable in directions that are parallel or antiparallel with the magnetization of the pinned layer. The free layer has a magnetic anisotropy the maintains the stability of the free layer magnetization. The free layer anisotropy is induced by a surface roughness either in the surface of the free layer itself, or in the surface of the underling barrier/spacer layer. This anisotropic roughness is induced by an angled direct ion milling.