Abstract: A patterned, synthetic, longitudinally exchange biased GMR sensor is provided which has a narrow effective trackwidth and reduced side reading. The advantageous properties of the sensor are obtained by satisfying a novel relationship between the magnetizations (M) of the ferromagnetic free layer (F1) and the ferromagnetic biasing layer (F2) which enables the optimal thicknesses of those layers to be determined for a wide range of ferromagnetic materials and exchange coupling materials. The relationship to be satisfied is MF2/MF1=(Js+Jex)/Js, where Js is the synthetic coupling energy between F1 and F2 and Jex is the exchange energy between F2 and an overlaying antiferromagnetic pinning layer. An alternative embodiment omits the overlaying antiferromagnetic pinning layer which causes the relationship to become MF2/MF1=1.

Abstract: A current-perpendicular-to-plane (CPP) giant magnetoresistive (GMR) sensor of the synthetic spin valve type is provided, the sensor comprising a GMR stack having a substantially square lateral cross-section, a Cu spacer layer of smaller square cross-section formed centrally on the GMR stack and a capped ferromagnetic free layer of substantially square, but even smaller cross-sectional area, formed centrally on the spacer layer. The stepped, reduced area geometry of the sensor provides a significant improvement in its GMR ratio (DR/R), a reduced resistance, R, and elimination of Joule heating hot-spots in regions of high resistance such as the antiferromagnetic pinning layer and its seed layer.

Abstract: A merged read/write magnetic recording head comprises a low magnetic moment first magnetic shield layer over a substrate. A read gap layer with a magnetoresistive head is formed over the first shield layer. A shared pole comprises a low magnetic moment second magnetic shield layer plated on a sputtered seed PLM layer over the read gap layer, a non-magnetic layer plated over the PLM layer and a HMM lower pole layer plated over the second magnetic shield layer. A write gap layer is formed over the first high magnetic moment pole layer of the shared pole. An upper pole comprises a high magnetic moment pole layer over the write gap layer.

Abstract: A patterned, synthetic, longitudinally exchange biased GMR sensor is provided which has a narrow effective trackwidth and reduced side reading. The advantageous properties of the sensor are obtained by satisfying a novel relationship between the magnetizations (M) of the ferromagnetic free layer (F1) and the ferromagnetic biasing layer (F2) which enables the optimal thicknesses of those layers to be determined for a wide range of ferromagnetic materials and exchange coupling materials. The relationship to be satisfied is MF2/MF1=(Js+Jex)/Js, where Js is the synthetic coupling energy between F1 and F2 and Jex is the exchange energy between F2 and an overlaying antiferromagnetic pinning layer. An alternative embodiment omits the overlaying antiferromagnetic pinning layer which causes the relationship to become MF2/MF1=1.

Abstract: A major problem in Lead Overlay design for GMR structures is that the magnetic read track width is wider than the physical read track width. This is due to high interfacial resistance between the leads and the GMR layer which is an unavoidable side effect of prior art methods. The present invention uses electroplating preceded by a wet etch to fabricate the leads. This approach requires only a thin protection layer over the GMR layer to ensure that interface resistance is minimal. Using wet surface cleaning avoids sputtering defects and plating is compatible with this so the cleaned surface is preserved Only a single lithography step is needed to define the track since there is no re-deposition involved.

Abstract: Nano-oxide based current-perpendicular-to-plane (CPP) magnetoresistive (MR) sensor stacks are provided, together with methods for forming such stacks. Such stacks have increased resistance and enhanced magnetoresistive properties relative to CPP stacks made entirely of metallic layers. Said enhanced properties are provided by the insertion of magnetic nano-oxide layers between ferromagnetic layers and non-magnetic spacer layers, whereby said nano-oxide layers increase resistance and exhibit spin filtering properties. CPP sensor stacks of various types are provided, all having nano-oxide layers formed therein, including the spin-valve type and the synthetic antiferromagnetic pinned layer spin-valve type. Said stacks can also be formed upon each other to provide laminated stacks of different types.

Abstract: A multiple-memory-layer magnetic random access memory (MRAM) has multiple memory layers arranged as pairs and stacked on a substrate. The first memory layer in the pair comprises a plurality of rows of memory cells located between electrically conductive access lines, and the second memory layer in the pair is substantially identical to the first memory layer, but is rotated about an axis perpendicular to the substrate so that the access lines and memory cell rows in one memory layer of the pair are orthogonal to their counterpart lines and rows in the other memory layer. The memory cells in each layer are aligned vertically (perpendicular to the substrate) with the memory cells in the other layer, with the vertically aligned memory cells forming memory cell columns that extend perpendicularly from the substrate. Each memory cell column has an electrical switch between the lowermost memory cell and the substrate.

Abstract: Nano-oxide based current-perpendicular-to-plane (CPP) magnetoresistive (MR) sensor stacks are provided, together with methods for forming such stacks. Such stacks have increased resistance and enhanced magnetoresistive properties relative to CPP stacks made entirely of metallic layers. Said enhanced properties are provided by the insertion of magnetic nano-oxide layers between ferromagnetic layers and non-magnetic spacer layers, whereby said nano-oxide layers increase resistance and exhibit spin filtering properties. CPP sensor stacks of various types are provided, all having nano-oxide layers formed therein, including the spin-valve type and the synthetic antiferromagnetic pinned layer spin-valve type. Said stacks can also be formed upon each other to provide laminated stacks of different types.

Abstract: It has been found that the insertion of a copper laminate within CoFe, or a CoFe/NiFe composite, leads to higher values of CPP GMR and DRA. However, this type of structure exhibits very negative magnetostriction, in the range of high ?10?6 to ?10?5. This problem has been overcome by giving the copper laminates an oxygen exposure treatment When this is done, the free layer is found to have a very low positive magnetostriction constant. Additionally, the value of the magnetostriction constant can be adjusted by varying the thickness of the free layer and/or the position and number of the oxygen treated copper laminates.

Abstract: Currently, the shield-to-shield separation of a spin valve head cannot be below about 800 ?, mainly due to sensor-to-lead shorting problems. This problem has now been overcome by inserting a high permeability, high resistivity, thin film shield on the top or bottom (or both) sides of the spin valve sensor. A permeability greater than about 500 is required together with a resistivity about 5 times greater than that of the free layer and an MrT value for the thin film shield that is 4 times greater than that of the free layer. Five embodiments of the invention are described.

Abstract: A “toggling” type of magnetic random access memory (MRAM) has memory stacks arranged in the X-Y plane on the MRAM substrate with each memory stack having a plurality of toggle memory cells stacked along the Z axis. Each memory stack is located at an intersection region between two orthogonal write lines. Each cell in the stack is a “toggle” cell that has its synthetic antiferromagnet (SAF) free layer easy axis of magnetization aligned nonparallel with the X and Y axes and angularly spaced about the Z axis from the easy axes of magnetization of all the other SAF free layers in the stack. Each cell in a stack is magnetically separated from adjacent cells in the stack by a nonmagnetic separation layer. The magnetization direction of the free layer in a selected memory cell in a stack can be switched without switching the magnetization directions of the free layers in the other memory cells in the stack.

Abstract: Increasing the output signal from CPP GMR devices by increasing the read current has not previously been considered an option because it would make the device run too hot. This problem has been overcome by using, for the upper and lower leads, materials that differ significantly in their thermoelectric powers. Thus, when DC is passed through the device, from ? to + TEP leads, hot and cold junctions are formed and heat is transferred from the micro-device into the leads, resulting in a net local cooling of the device which enables it to operate at higher power. For a GMR device, this translates to a larger output voltage, making it easier, more sensitive, and more reliable to use.

Abstract: Nano-oxide based current-perpendicular-to-plane (CPP) magnetoresistive (MR) sensor stacks are provided, together with methods for forming such stacks. Such stacks have increased resistance and enhanced magnetoresistive properties relative to CPP stacks made entirely of metallic layers. Said enhanced properties are provided by the insertion of magnetic nano-oxide layers between ferromagnetic layers and non-magnetic spacer layers, whereby said nano-oxide layers increase resistance and exhibit spin filtering properties. CPP sensor stacks of various types are provided, all having nano-oxide layers formed therein, including the spin-valve type and the synthetic antiferromagnetic pinned layer spin-valve type. Said stacks can also be formed upon each other to provide laminated stacks of different types.

Abstract: Reduction of the free layer thickness in GMR devices is desirable in order to meet higher signal requirements, besides improving the GMR ratio itself. However, thinning of the free layer reduces the GMR ratio and leads to poor thermal stability. This problem has been overcome by making AP2 from an inverse GMR material and by changing the free layer from a single uniform layer to a ferromagnetic layer AFM (antiferromagnetically) coupled to a layer of inverse GMR material. Examples of alloys that may be used for the inverse GMR materials include FeCr, NiFeCr, NiCr, CoCr, CoFeCr, and CoFeV. Additionally, the ruthenium layer normally used to effect antiferromagnetic coupling can be replaced by a layer of chromium. A process to manufacture the structure is also described.

Abstract: A magnetic random access memory (MRAM) has multiple stacked memory layers, with each memory layer being a plurality of alternating rows of memory cells and electrically conductive access lines. The access lines in each layer are aligned with the access lines in the layers above and below. Similarly the memory cell rows in each layer are aligned with the memory cell rows in the layers above and below, with the memory cells in adjacent layers forming memory cell columns that extending perpendicularly from the MRAM substrate. The memory cells are connected to bit and word lines for addressing selected cells. The MRAM includes electrical circuitry connected to the access lines for directing currents through the access lines in the memory layer of the selected cell and in the access lines directly above or below to generate magnetic fields that switch the magnetic state of the selected cell without switching the magnetic state of non-selected cells in the memory layers above and below.

Abstract: A GMR read head is described. The device comprises a spin valve stack whose top layer is a first capping layer. On the first capping layer are two additional layers, a lead overlay layer and a second capping layer. These are divided into two opposing portions, separated from each other by a trench that is filled with a dielectric. A bias layer and a conductive lead layer contact the stack on its sidewalls.

Abstract: Nano-oxide based current-perpendicular-to-plane (CPP) magnetoresistive (MR) sensor stacks are provided, together with methods for forming such stacks. Such stacks have increased resistance and enhanced magnetoresistive properties relative to CPP stacks made entirely of metallic layers. Said enhanced properties are provided by the insertion of magnetic nano-oxide layers between ferromagnetic layers and non-magnetic spacer layers, whereby said nano-oxide layers increase resistance and exhibit spin filtering properties. CPP sensor stacks of various types are provided, all having nano-oxide layers formed therein, including the spin-valve type and the synthetic antiferromagnetic pinned layer spin-valve type. Said stacks can also be formed upon each other to provide laminated stacks of different types.

Abstract: A major problem in Lead Overlay design for GMR structures is that the magnetic read track width is wider than the physical read track width. This is due to high interfacial resistance between the leads and the GMR layer which is an unavoidable side effect of prior art methods. The present invention uses electroplating preceded by a wet etch to fabricate the leads. This approach requires only a thin protection layer over the GMR layer to ensure that interface resistance is minimal. Using wet surface cleaning avoids sputtering defects and plating is compatible with this so the cleaned surface is preserved Only a single lithography step is needed to define the track since there is no re-deposition involved.

Abstract: A method for forming top and bottom spin valve sensors and the sensors so formed, the sensors having a strongly coupled SyAP pinned layer and an ultra-thin antiferromagnetic pinning layer. The two strongly coupled ferromagnetic layers comprising the SyAP pinned layer in the top valve configuration are separated by a Ru spacer layer approximately 3 angstroms thick, while the two layers in the bottom spin valve configuration are separated by a Rh spacer layer approximately 5 angstroms thick. This allows the use of an ultra thin MnPt antiferromagnetic pinning layer of thickness between approximately 80 and approximately 150 angstroms. The sensor structure produced thereby is suitable for high density applications.

Abstract: In a single vertical pole magnetic writer, flux passing through the return pole can sometimes be strong enough to erase previously recorded data. This problem has been overcome by the addition of a second return pole that is magnetically connected to the conventional return pole for the purpose of collecting leaked flux, thereby preventing it from reaching the underlayer.