Patents by Inventor Daniel A. Nepela
Daniel A. Nepela has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7482298Abstract: The composition of compounds containing a multiplicity of different elements are optimized in general by full or partial substitutions of one or more of the atoms in such compounds so as to effect an Ne/? value which represents a peak or near peak value in ? (the electron-phonon coupling constant) so as to maximize Tc for such compositions of matter.Type: GrantFiled: November 27, 2006Date of Patent: January 27, 2009Inventor: Daniel A. Nepela
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Publication number: 20080125323Abstract: The composition of compounds containing a multiplicity of different elements are optimized in general by full or partial substitutions of one or more of the atoms in such compounds so as to effect an Ne/? value which represents a peak or near peak value in ? (the electron-phonon coupling constant) so as to maximize Tc for such compositions of matter.Type: ApplicationFiled: November 27, 2006Publication date: May 29, 2008Inventor: Daniel A. Nepela
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Patent number: 6828897Abstract: A method for maximizing the interfacial properties of magnetoresistive sensors, such as spin valve and GMR sensors used in storage devices, comprises selecting the materials for ferromagnetic layers and for electrically conductive spacers that are interposed between the ferromagnetic layers. The electronegativities of the selected materials are substantially matched so that an absolute value of the differences in electronegativities is minimized. The conductive spacer material provides a relatively low resistivity and a large mean free path. The sensors experience greater chemical and thermal stability, are corrosion resistant, and realize an increased signal output.Type: GrantFiled: August 3, 1998Date of Patent: December 7, 2004Assignee: Western Digital (Fremont), Inc.Inventor: Daniel A. Nepela
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Publication number: 20020114113Abstract: A magnetoresistive (MR) read sensor fabricated on a substrate includes a ferromagnetic layer that is exchange coupled with an antiferromagnetic layer made of a defined composition of iridium manganese. A tantalum layer is used so that the exchange field and coercivity do not change with variations in annealing temperature. The antiferromagnetic layer is formed with a material composition of IrxMn100-x wherein x is in the range of 15<x>23. In an embodiment of a spin valve structure, the tantalum layer is disposed over the substrate and the antiferromagnetic layer is in direct contact with a pinned ferromagnetic layer. In another embodiment, the IrMn layer is formed over a soft active layer. In a third embodiment using exchange pinning, spaced IrMn regions are formed over the active MR layer to define the sensor track width.Type: ApplicationFiled: March 28, 2002Publication date: August 22, 2002Inventors: Marcos M. Lederman, Daniel A. Nepela, Hua-Ching Tong
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Patent number: 6424507Abstract: A magnetoresistive read sensor fabricated on a substrate includes a ferromagnetic layer that is exchange coupled with an antiferromagnetic layer made of a defined composition of iridium manganese. A tantalum layer is used so that the exchange field and coercivity do not change with variations in annealing temperature. The antiferromagnetic layer is formed with a material composition of Irx Mn100-x, wherein x is in the range of 15<x>23. In an embodiment of a spin valve structure, the tantalum layer is disposed over the substrate and the antiferromagnetic layer is in direct contact with a pinned ferromagnetic layer. In another embodiment, the IrMn layer is formed over a soft active layer. In a third embodiment using exchange pinning, spaced IrMn regions are formed over the active magnetoresistive layer to define the sensor track width.Type: GrantFiled: April 3, 2000Date of Patent: July 23, 2002Assignee: Read-Rite CorporationInventors: Marcos M. Lederman, Daniel A. Nepela, Hua-Ching Tong
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Patent number: 6330131Abstract: An air bearing slider for a magnetic head assembly is configured with taper flat outer rails and a recessed region between the rails in one embodiment of the invention, a hard wear-resistant layer is deposited over part of the rail area, with a thin residual layer over the remainder of the slider area, yielding a step in thickness near the load point. In another embodiment, the wear resistant layer appears only on the side rails. In an alternative embodiment using a tripad configuration of the air bearing surface, the hard wear-resistant layer is disposed on portions of all three pads. The invention allows control and minimization of the stiction forces between an air bearing slider and a magnetic disk, particularly during liftoff at the start of disk drive operation.Type: GrantFiled: September 17, 1993Date of Patent: December 11, 2001Assignee: Read-Rite CorporationInventors: Daniel A. Nepela, Paul H. Schmidt
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Patent number: 6166891Abstract: A magnetoresistive read sensor fabricated on a substrate includes a ferromagnetic layer that is exchange coupled with an antiferromagnetic layer made of a defined composition of iridium manganese. A tantalum layer is used so that the exchange field and coercivity do not change with variations in annealing temperature. The antiferromagnetic layer is formed with a material composition of Ir.sub.x Mn.sub.100-x, wherein x is in the range of 15<.times.>23. In an embodiment of a spin valve structure, the tantalum layer is disposed over the substrate and the antiferromagnetic layer is in direct contact with a pinned ferromagnetic layer. In another embodiment, the IrMn layer is formed over a soft active layer. In a third embodiment using exchange pinning, spaced IrMn regions are formed over the active magnetoresistive layer to define the sensor track width.Type: GrantFiled: June 30, 1997Date of Patent: December 26, 2000Assignee: Read-Rite CorporationInventors: Marcos M. Lederman, Daniel A. Nepela, Hua-Ching Tong
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Patent number: 6163426Abstract: A magnetoresistive head achieves maximum signal output with minimal electromigration by using a magnetoresistive element through which a unidirectional sense current is flown. Periodically, a control circuit determines whether one or more switching criteria have been met, and applies a counter-directional compensation current in the magnetoresistive element when the switching criteria are met, thus suppressing electromigration in the magnetoresistive element in the direction of said sense current. In a preferred embodiment, the compensation current is applied during a quiescence period.Type: GrantFiled: July 8, 1998Date of Patent: December 19, 2000Assignee: Read Rite CorporationInventors: Daniel Nepela, Chung F Lam
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Patent number: 6137662Abstract: A magnetoresistive sensor including a magnetoresistive (MR) sensing element, a nonmagnetic layer ("spacer") contacting the magnetoresistive sensing element; a first antiferromagnetic (AFM) layer contacting the nonmagnetic layer such that the nonmagnetic layer is sandwiched between the magnetoresistive sensing element and the antiferromagnetic layer; a ferromagnetic soft adjacent layer (SAL) contacting the antiferromagnetic layer such that the antiferromagnetic layer is sandwiched between the nonmagnetic layer and the soft adjacent layer; and a second antiferromagnetic layer contacting the SAL such that the SAL is sandwiched between the first and second antiferromagnetic layers. The two antiferromagnetic layers provide a stronger pinning effect. In one embodiment of the invention, the magnetoresistive sensing element is an anisotropic magnetoresistive (AMR) sensing element comprising a soft ferromagnetic layer.Type: GrantFiled: April 7, 1998Date of Patent: October 24, 2000Assignee: Read-Rite CorporationInventors: Yiming Huai, Daniel Nepela, Durga Ravipati, Marcos Lederman
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Patent number: 6078479Abstract: A thin film read-write magnetic head useful in a tape apparatus includes a magnetic circuit consisting of two thin film magnetic layers which form a magnetic yoke that is divided into three closely spaced sections, the central section of at least one of the magnetic layers containing an interspace in which a flux sensing element, such as a magnetoresistive device or Hall effect device, is located. The three section yoke forms a continuous magnetic circuit, except for the transducing gap, which circuit consists of three sections corresponding to the three sections of the yoke. The total gap width determines the width of the data track being recorded. During the write mode, a magnetic valve including an electrical conductor provides a shunt path to bypass the flux sensing means so that all three sections of the head operate for recording.Type: GrantFiled: July 11, 1995Date of Patent: June 20, 2000Assignee: Read-Rite CorporationInventors: Daniel A. Nepela, Erich P. Valstyn, Derek Jan Kroes
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Patent number: 5961746Abstract: The magnetic metal composition of a Co-based alloy includes additives to produce an amorphous condition in the alloy and also includes amounts of Rh to increase the corrosion resistance of the alloy. By adding the amorphous-producing materials and selected amounts of Rh, the corrosion resistance of the resulting Co-based alloys has been found to be considerably improved over that of the base amorphous Co alloy without rhodium.Type: GrantFiled: August 15, 1997Date of Patent: October 5, 1999Assignee: Read-Rite CorporationInventor: Daniel A. Nepela
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Patent number: 5949627Abstract: A thin film magnetic head is fabricated having soft metal layers of 0.25 to 1 micron thickness disposed on each side of the first and second magnetic layers of Permalloy forming the magnetic yoke. The soft layers are formed between the ceramic substrate and the first Permalloy layer, between the first Permalloy layer and the insulation surrounding the electrical coil of the head, between the insulation and the second Permalloy layer, and between the second Permalloy layer and the insulating overcoat of the head. The soft metal has a coefficient of thermal expansion between that of the Permalloy and that of the ceramic substrate and insulation materials. In this way, stress buffers are provided to minimize the mismatch and thermal stress transfer between the Permalloy and the other materials of the adjacent layers, resulting in improved domain stability and a significant reduction in popcorn noise.Type: GrantFiled: February 19, 1993Date of Patent: September 7, 1999Assignee: Read-Rite CorporationInventors: Edgar M. Williams, Peter G. Bischoff, Daniel A. Nepela
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Patent number: 5920979Abstract: A low noise inductive magnetic head used for writing and reading magnetic signals onto and from a magnetic recording medium includes two magnetic poles P1, P2 that are formed on a substrate which define a transducing gap therebetween. Each of the poles P1, P2 includes an outer magnetic layer formed remotely from the gap and an inner magnetic layer formed adjacent to the gap. The inner and outer magnetic layers have magnetostrictions (.lambda..sub.s) of approximately equal but opposite values, such that each of the magnetic poles P1, P2 exhibits a net magnetostriction of zero or is biased within a predefined range, regardless of the individual magnetostriction values of its layers.Type: GrantFiled: November 17, 1997Date of Patent: July 13, 1999Assignee: Read-Rite CorporationInventors: Daniel A. Nepela, Siamak Sarhadi
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Patent number: 5917680Abstract: A magnetoreristive head assembly has a magnetic bias level control for continuous compensation of thermal, stray field and stress fluctuations, as well as other types of fluctuations. The magnetoresistive head assembly includes a magnetoresistive element for sensing signals recorded on a magnetic medium, and for generating electrical signals corresponding to the recorded signals. A bias current balancing circuit has an input connected to the magnetoresistive element for sensing the electrical signals and for generating a correction bias current therefrom. A feedback correction circuit converts the correction bias current into a correction magnetic bias field and applies the field to the magnetoresistive element to limit the shifting of a current bias point of the magnetoresistive element and to compensate for bias fluctuations.Type: GrantFiled: June 24, 1996Date of Patent: June 29, 1999Assignee: Read-Rite CorporationInventors: Erich P. Valstyn, Charles R. Bond, Daniel A. Nepela
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Patent number: 5793550Abstract: A magnetoresistive head achieves maximum signal output with minimal electromigration by use of two increased direct currents with different polarities which are directed periodically through a magnetoresistive element in opposite directions, with minimal long term directional diffusion for minimizing electromigration and for increasing the signal output. The magnetoresistive element defines two magnetic centers MC.sup.+ and MC.sup.- that correspond to the polarities of the two currents, and the magnetic centers are positioned at optimal magnetic locations.Type: GrantFiled: April 23, 1996Date of Patent: August 11, 1998Assignee: Read-Rite CorporationInventors: Daniel A. Nepela, Amritpal S. Rana
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Patent number: 5793279Abstract: A method for maximizing the interfacial properties of magnetoresistive sensors, such as spin valve and GMR sensors used in storage devices, comprises selecting the materials for ferromagnetic layers and for electrically conductive spacers that are interposed between the ferromagnetic layers. The electronegativities of the selected materials are substantially matched so that an absolute value of the differences in electronegativities is minimized. The conductive spacer material provides a relatively low resistivity and a large mean free path. The sensors experience greater chemical and thermal stability, are corrosion resistant, and realize an increased signal output.Type: GrantFiled: August 26, 1996Date of Patent: August 11, 1998Assignee: Read-Rite CorporationInventor: Daniel A. Nepela
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Patent number: 5768073Abstract: A magnetic thin film head with reduced undershoot characteristics includes a pair of relatively high permeability pole members having a low permeability gap member therebetween. Disposed adjacent to the surfaces of the pole members, which are opposite to the gap member, are layers of magnetic material of lower permeability than the permeability of the pole members, these lower permeability layers having a Curie point temperature which is within the operating temperature range of the head so that these lower permeability layers are paramagnetic. In operation, the lower permeability layers provide a change in permeability across the head gap which reduces the transition in permeability at the head pole tips, thereby reducing undershoots.Type: GrantFiled: February 7, 1997Date of Patent: June 16, 1998Assignee: Read-Rite CorporationInventors: Daniel A. Nepela, Charles R. Bond
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Patent number: 5751528Abstract: A low noise inductive magnetic head used for writing and reading magnetic signals onto and from a magnetic recording medium includes two magnetic poles P1, P2 that are formed on a substrate which define a transducing gap therebetween. Each of the poles P1, P2 includes an outer magnetic layer formed remotely from the gap and an inner magnetic layer formed adjacent to the gap. The inner and outer magnetic layers have magnetostrictions (.lambda..sub.s) of approximately equal but opposite values, such that each of the magnetic poles P1, P2 exhibits a net magnetostriction of zero or is biased within a predefined range, regardless of the individual magnetostriction values of its layers.Type: GrantFiled: April 15, 1996Date of Patent: May 12, 1998Assignee: Read-Rite CorporationInventors: Daniel A. Nepela, Siamak Sarhadi
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Patent number: 5742162Abstract: A magnetic sensing structure includes a spin valve sensor having a pinned magnetic layer and a free magnetic layer, the direction of magnetization of the free layer varying as a function of the magnetic field applied to the structure. A multilayered magnetic keeper structure is provided to cancel the magnetostatic field from the pinned layer to provide an ideal bias profile for the structure in the absence of an applied magnetic field. Longitudinal magnetic bias may be applied to the spin valve sensor through a contiguous junction magnetic structure adjacent to the keeper structure and spin valve sensor.Type: GrantFiled: July 17, 1996Date of Patent: April 21, 1998Assignee: Read-Rite CorporationInventors: Daniel A. Nepela, Marcos M. Lederman
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Patent number: 5742459Abstract: A magnetic head assembly includes a read head having an active central region and two inactive side regions contiguously formed relative to the central region. The central region includes a magnetoresistive (MR) transducer for enabling active sensing of data recorded on a magnetic medium. Protective layers encapsulate the central region and separate it from the side regions, such that diffusion and electromigration are reduced. Each end region includes a longitudinal bias layer, and a multilayered conductive section. The longitudinal bias layer may be formed of alternating layers of antiferromagnetic material and layers of soft magnetic material and/or hard magnetic longitudinal bias. The multilayered conductive section includes conductive leads that do not contact either the MR element or the soft bias layer.Type: GrantFiled: June 20, 1996Date of Patent: April 21, 1998Assignee: Read-Rite CorporationInventors: Yong Shen, Chyu Jiuh Torng, Daniel A. Nepela