摘要:
A current-perpendicular-to-the-plane spin-valve (CPP-SV) magnetoresistive sensor has an insulating layer with at least one aperture that confines the flow of sense current through the active region. The apertures are located closer to the sensing edge of the sensor than to the back edge of the sensor. The aperture (or apertures) are patterned by e-beam lithography, which enables the number, size and location of the apertures to be precisely controlled. The insulating layer may be located inside the electrically conductive nonmagnetic spacer layer, or outside of the magnetically active layers of the spin-valve. More than one insulating layer may be included in the stack to define conductive current paths where the apertures of the insulating layers overlap. The apertures are filled with electrically conductive material, typically the same material as that used for the spacer layer.
摘要:
A current-perpendicular-to-the-plane (CPP) magnetoresistive sensor has an antiparallel free (APF) structure as the free layer and a specific direction for the applied bias or sense current. The (APF) structure has a first free ferromagnetic (FL1), a second free ferromagnetic layer (FL2), and an antiparallel (AP) coupling (APC) layer that couples FL1 and FL2 together antiferromagnetically with the result that FL1 and FL2 have substantially antiparallel magnetization directions and rotate together in the presence of a magnetic field. The thicknesses of FL1 and FL2 are chosen to obtain the desired net free layer magnetic moment/area for the sensor, and the thickness of FL1 is preferably chosen to be greater than the spin-diffusion length of the electrons in the FL1 material to maximize the bulk spin-dependent scattering of electrons and thus maximize the sensor signal. The CPP sensor operates specifically with the conventional sense current (opposite the electron current) directed from the pinned ferromagnetic layer to the APF structure, which results in suppression of current-induced noise.
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:
A magnetoresistive sensor having a magnetic anisotropy induced in one or both of the free layer and/or pinned layer. The magnetic anisotropy is induced by a surface texture formed in the surface of the magnetic layer of either or both of the free layer or pinned layer. The surface texture is formed by a direct, angled ion mill performed on the surface of the magnetic layer while holding the wafer on a stationary chuck. By applying this ion milling technique, the magnetic anisotropy of the pinned layer can be formed in a first direction (eg. perpendicular to the ABS) while the magnetic anisotropy of the free layer can be formed perpendicular to that of the pinned layer (eg. parallel to the ABS).
摘要:
A magnetoresistive sensor having improved pinning field strength. The sensor includes a pinned layer structure pinned by exchange coupling with an antiferromagnetic (AFM) layer. The AFM layer is constructed upon an under layer having treated surface with an anisotropic roughness. The anisotropic roughness, produced by an angled ion etch, results in improved pinning strength. The underlayer may include a seed layer and a thin layer of crystalline material such as PtMn formed over the seed layer. The magnetic layer may include a first sub-layer of NiFeCr and a second sub-layer of NiFe formed there over. The present invention also includes a magnetoresistive sensor having a magnetic layer deposited on an underlayer (such as a non-magnetic spacer) having a surface treated with an anisotropic texture. An AFM layer is then deposited over the magnetic layer. The magnetic layer is then strongly pinned by a combination of exchange coupling with the AFM layer and a strong anisotropy provided by the surface texture of the underlayer. Such a structure can be used for example in a sensor having a pinned layer structure formed above the free layer, or in a sensor having an in stack bias structure.
摘要:
A current-perpendicular-to-the-plane spin-valve (CPP-SV) magnetoresistive sensor has an improved antiparallel (AP) pinned structure, i.e., a structure with first (AP1) and second (AP2) ferromagnetic layers separated by a nonmagnetic antiparallel coupling (APC) layer with the magnetization directions of AP1 and AP2 oriented substantially antiparallel. The AP2 ferromagnetic layer (the layer in contact with the SV spacer layer) is an alloy of a ferromagnetic material and one or more additive elements of Cu, Au and Ag. The additive elements reduce the magnetic moment of the AP2 layer, which enables its thickness to be increased so that its magnetic moment remains close to the magnetic moment of the AP1 ferromagnetic layer. The thicker AP2 layer allows for more bulk spin-dependent scattering of electrons which increases the magnetoresistance of the sensor. An annealed AP2 layer results in more segregation of the ferromagnetic material grains and the additive element grains, and thus a further improvement in magnetoresistance as a result of more interfacial scattering of electrons.
摘要:
A magnetoresistive sensor having a hard bias layer with an engineered magnetic anisotropy in a direction substantially parallel with the medium facing surface. The hard 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 induce anisotropic roughness on its surface for example 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 bias layers deposited there over.
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:
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.