Patents by Inventor Prakash Kasiraj
Prakash Kasiraj 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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Publication number: 20050190509Abstract: A spin valve (SV) sensor of the self-pinned type includes one or more compressive stress modification layers for reducing the likelihood that the pinning field will flip its direction. The spin valve sensor includes a capping layer formed over a spin valve structure which includes a free layer, an antiparallel (AP) self-pinned layer structure, and a spacer layer in between the free layer and the AP self-pinned layer structure. A compressive stress modification layer is formed above or below the capping layer, adjacent the AP self-pinned layer structure, or both. Preferably, the compressive stress modification layer is made of ruthenium (Ru) or other suitable material.Type: ApplicationFiled: February 27, 2004Publication date: September 1, 2005Inventors: Ciaran Fox, Hardayal Gill, Prakash Kasiraj, Wen-Yaung Lee, Mustafa Pinarbasi
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Publication number: 20050180062Abstract: Magnetic data storage devices use read/write heads to transfer data between the magnetic storage medium and the rest of the system. The read head is constructed with a magnetic layer called a free layer whose magnetic axis rotates based upon external magnetic influences of the magnetic storage medium. The free layer is biased into a predetermined magnetic orientation with the magnetic influence of a layer called a hard bias layer. Orientation of magnetic axes within the hard bias layer is desired. This document describes a hard bias layer whose magnetization exhibits uniaxial magnetic anisotropy.Type: ApplicationFiled: February 18, 2004Publication date: August 18, 2005Inventors: Kuok Ho, Prakash Kasiraj, Ernesto Marinero, James Nix
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Publication number: 20050180064Abstract: A magnetic sensor is provided, having two bias layers separated by a decoupling layer to eliminate exchange coupling between the bias layers. The two bias layers may have differing coercivities, such that the biases provided by the bias layers to the free layer are independently adjustable. The grain structures of the two bias layers may be substantially decorrelated by the decoupling layer.Type: ApplicationFiled: February 18, 2004Publication date: August 18, 2005Inventors: Marie-Claire Cyrille, Meng Ding, Kuok-San Ho, Prakash Kasiraj, Ernesto Marinero, James Nix, Brian York
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Publication number: 20050180063Abstract: A magnetic sensor is provided, having two bias layers separated by a decoupling layer to eliminate exchange coupling between the bias layers. The two bias layers may have differing coercivities, such that the biases provided by the bias layers to the free layer are independently adjustable. The grain structures of the two bias layers may be substantially decorrelated by the decoupling layer.Type: ApplicationFiled: February 18, 2004Publication date: August 18, 2005Inventors: Marie-Claire Cyrille, Meng Ding, Kuok Ho, Prakash Kasiraj, Ernesto Marinero, James Nix
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Publication number: 20050174701Abstract: A current-perpendicular-to-the-plane (CPP) magnetoresistive sensor has additional layers for stabilizing the free layer against sense-current-generated magnetic fields. A ferromagnetic stabilizing layer is spaced from the free layer by a spacer layer and is exchange coupled with a second antiferromagnetic layer, the first antiferromagnetic layer being the conventional one for pinning the pinned layer in the CPP sensor. The stabilizing layer is in a vortex or other non-longitudinal magnetization pattern that is fixed by exchange coupling with the second antiferromagnetic layer. The stabilizing layer is also ferromagnetically coupled to the free layer across the spacer layer so that in the absence of both a sense current and an external magnetic field, the free and stabilization layers have similarly shaped vortex or other non-longitudinal magnetization patterns.Type: ApplicationFiled: February 10, 2004Publication date: August 11, 2005Inventors: Prakash Kasiraj, Stefan Maat
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Patent number: 6901653Abstract: A Damascene process is provided for manufacturing a coil structure for a magnetic head. During the manufacturing process, an insulating layer is initially deposited after which a photoresist layer is deposited. A silicon dielectric layer is then deposited on the photoresist layer. After masking the silicon dielectric layer, at least one channel is etched in the photoresist layer and the silicon dielectric layer. Then, a conductive seed layer is deposited in the at least one channel. The at least one channel is then ready to be filled with a conductive material and chemically/mechanically polished to define a coil structure.Type: GrantFiled: April 2, 2002Date of Patent: June 7, 2005Assignee: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Richard Hsiao, Prakash Kasiraj, Quang Le, Paul Phong Nguyen, Son Van Nguyen, Denny D. Tang, Patrick Rush Webb
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Publication number: 20050068664Abstract: Data is written to a hard disk drive using shingled writing principles, i.e., each data track is partially overwritten when an immediately contiguous data track is written. Two or more contiguous data tracks establish a band, and a band may store data from an AV file. Tracks may be written in sequence toward or away from the inside diameter (ID) of the disk, depending on their radial location on the disk and the skew of the write element.Type: ApplicationFiled: September 29, 2003Publication date: March 31, 2005Applicant: Hitachi Global Storage TechnologiesInventors: Prakash Kasiraj, Mason Williams
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Publication number: 20050070206Abstract: A slider is described with a resistive electro-lapping guide (ELG), which is aligned with a structure in the write head such as the throat height or trailing shield thickness and extends from the lapping region through the ABS and is connected to pads on the surface of the slider. In a second embodiment the ELG is disposed entirely in the section of the slider which will be removed by lapping. Another embodiment of the invention is a system for single slider lapping which simultaneously monitors the resistance of the read sensor or a read head ELG and at least one ELG that is aligned with a structure in the write head. A controller uses the resistance information to implement an algorithm which decides when lapping should be terminated.Type: ApplicationFiled: September 29, 2003Publication date: March 31, 2005Inventors: Prakash Kasiraj, Quang Le, Huey Tzeng, Xiao Wu
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Publication number: 20050069298Abstract: Data is written to a hard disk drive using shingled writing principles, i.e., each data track is partially overwritten when an immediately contiguous data track is written. Two or more contiguous data tracks establish a band, and a band may store data from one and only one file, such as an AV file.Type: ApplicationFiled: September 29, 2003Publication date: March 31, 2005Applicant: Hitachi Global Storage TechnologiesInventors: Prakash Kasiraj, Richard New, Jorge de Souza, Mason Williams
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Publication number: 20040177493Abstract: A Damascene process is provided for manufacturing a coil structure for a magnetic head. During the manufacturing process, an insulating layer is initially deposited after which a photoresist layer is deposited. A silicon dielectric layer is then deposited on the photoresist layer. After masking the silicon dielectric layer, at least one channel is etched in the photoresist layer and the silicon dielectric layer. Then, a conductive seed layer is deposited in the at least one channel. The at least one channel is then ready to be filled with a conductive material and chemically/mechanically polished to define a coil structure.Type: ApplicationFiled: March 31, 2004Publication date: September 16, 2004Inventors: Richard Hsiao, Prakash Kasiraj, Quang Le, Paul Phong Nguyen, Son Van Nguyen, Denny D. Tang, Patrick Rush Webb
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Publication number: 20040075938Abstract: A Damascene process is provided for manufacturing a coil structure for a magnetic head. During the manufacturing process, an insulating layer is initially deposited after which a photoresist layer is deposited. A silicon dielectric layer is then deposited on the photoresist layer. After masking the silicon dielectric layer, at least one channel is etched in the photoresist layer and the silicon dielectric layer. Then, a conductive seed layer is deposited in the at least one channel. The at least one channel is then ready to be filled with a conductive material and chemically/mechanically polished to define a coil structure.Type: ApplicationFiled: November 19, 2003Publication date: April 22, 2004Applicant: HITACHI GLOBAL STORAGE TECHNOLOGIESInventors: Richard Hsiao, Prakash Kasiraj, Quang Le, Paul Phong Nguyen, Son Van Nguyen, Denny D. Tang, Patrick Rush Webb
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Publication number: 20030184912Abstract: A Damascene process is provided for manufacturing a coil structure for a magnetic head. During the manufacturing process, an insulating layer is initially deposited after which a photoresist layer is deposited. A silicon dielectric layer is then deposited on the photoresist layer. After masking the silicon dielectric layer, at least one channel is etched in the photoresist layer and the silicon dielectric layer. Then, a conductive seed layer is deposited in the at least one channel. The at least one channel is then ready to be filled with a conductive material and chemically/mechanically polished to define a coil structure.Type: ApplicationFiled: April 2, 2002Publication date: October 2, 2003Applicant: INTERNATIONAL BUSINESS MACHINESInventors: Richard Hsiao, Prakash Kasiraj, Quang Le, Paul Phong Nguyen, Son Van Nguyen, Denny D. Tang, Patrick Rush Webb
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Patent number: 6603623Abstract: A method for forming a termination for a magnetic write head in which a magnetic write coil having an inner turn and an outer turn is formed on a wafer. A bottom capacitor plate for a capacitor on the wafer. A resistor having a first terminal and a second terminal is also formed on the wafer. A dielectric layer is formed over the bottom capacitor plate for the capacitor. A top capacitor plate is formed on the dielectric layer. An overpass lead is formed between the inner turn of the coil and one of the bottom capacitor plate and the top capacitor plate. The first terminal of resistor is connected to the capacitor plate that is not connected to the inner turn of the write coil. The second terminal of the resistor is connected to the outer turn of the write coil. An impedance formed by the write coil, the capacitor and the resistor substantially equals a characteristic impedance Z0 of an interconnect circuit that will be connected to the write coil.Type: GrantFiled: April 24, 2000Date of Patent: August 5, 2003Assignee: International Business Machines CorporationInventors: Robert E. Fontana, Jr., Prakash Kasiraj, Klaassen Berend Klaassen, Mason Lamar Williams
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Patent number: 6493183Abstract: A thermally-assisted magnetic recording disk drive records data by heating a small region of the magnetic layer on the disk to near or above its Curie temperature while a write field is applied by a thin film inductive write head. The thin film inductive write head includes an electrically resistive heater located in the write gap between the pole tips of the write head. The resistive heater is sandwiched between first and second spacer layers that are located between the pole tips of the write head. In a current-perpendicular-to-the plane (CPP) embodiment, the spacer layers are electrically conductive and the pole tips serve as the electrical leads to provide electrical current in a direction generally perpendicular to the layer of resistive heater material. In a current-in-the plane (CIP) embodiment, the spacer layers are formed of insulating material and electrical leads are formed as portions of a film between the spacer layers and in contact with each side of the resistive heater.Type: GrantFiled: June 29, 2000Date of Patent: December 10, 2002Assignee: International Business Machines CorporationInventors: Prakash Kasiraj, Neil Leslie Robertson, Hemantha Kumar Wickramasinghe
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Patent number: 6344949Abstract: Flying height Adjustment for Air Bearing Sliders An air bearing slider for sliding over a medium surface of a recording medium and having an air bearing surface facing the disk surface, a back surface perpendicular to the air bearing surface and a head at the back surface. During operation the head is maintained at a flying height above the disk surface with the aid of a flying height adjustment mechanism consisting of one or more ducts, each having an inlet at the air bearing surface and an outlet at the back surface. A valve mechanism controls an air flow through the duct or ducts by opening and closing the valve or valves together or independently. Alternatively, a deformable surface feature located on the back surface of the slider is used to alter the air flow to thus control the flying height. The mechanism of the invention allows one to achieve accurate flying height control in a range between 5 and 50 nm and between 0 nm and 15 nm as required for near-field or contact disk drives.Type: GrantFiled: July 13, 1999Date of Patent: February 5, 2002Assignee: International Business Machines CorporationInventors: Thomas Robert Albrecht, Robert Edward Fontana, Jr., Prakash Kasiraj, Erno Hilbrand Klaassen, Robert Nolan Payne, Timothy Clark Reiley
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Patent number: 6259583Abstract: The present invention is a magnetic head which has a preferably planar pole member having a yoke and a tip with a first planar pole P1 and a second planar pole P2 positioned above pole P1. The pole member is built up of two types of layers: a first type of layer with high magnetic permeability &mgr; and low anisotropy Hk, with the easy axis oriented substantially perpendicular to the flux propagation direction to ensure rapid response, and a second layer type which is non-magnetic. The magnetic head also has a domain control element whose magnetization in the vicinity of the pole tip P2 and in the absence of applied field is aligned along the length of the element so as to facilitate the conduction of flux between poles P1 and P2. The domain control element can be a non-laminated element made of a material with high saturation magnetization MS such as NiFe, Ni80Fe20, Ni45Fe55, NiFeCo, FeCo, CoZrNb, FeAlN and FeTaN and proper dimensioning of the element further increases the flux conduction efficiency.Type: GrantFiled: September 16, 1998Date of Patent: July 10, 2001Assignee: International Business Machines, CorporationInventors: Robert Edward Fontana, Jr., Yimin Hsu, Prakash Kasiraj, Mason Lamar Williams
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Patent number: 6137644Abstract: A method for adaptively formatting the multiple surfaces of data storage devices such as hard drives. The method ensures that all the drives have the same total data capacity and that the capacity in each data rate is the same from drive to drive. The method includes the step of dividing the data surfaces into warm and cold surfaces using a surface quality measurement. All cold surfaces are formatted with a predetermined cold format and all warm surfaces are formatted with a predetermined warm format. The cold and warm formats have different data capacities by means of different zone layouts, a different number of error correction code bytes per data block, or different track pitches. A second embodiment uses one of three different formats for each surface: cold, nominal, or hot. The cold and hot formats are designed to be mutually compensating in terms of data capacity and each drive has an equal number of cold and hot surfaces.Type: GrantFiled: May 19, 1998Date of Patent: October 24, 2000Assignee: International Business Machines CorporationInventors: Steven R. Hetzler, Prakash Kasiraj, Richard M. H. New
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Patent number: 5777815Abstract: A magnetic recording disk drive with a magnetoresistive (MR) read sensor or head has a shock and vibration detection circuitry responsive to a thermoresistive signal contained in the signal from the head. The MR head is heated by an electrical bias current and is supported on the head carrier near the surface of the disk. External shock or vibration to the disk drive alters the spacing between the carrier and the disk, which causes fluctuations in the head temperature due to cooling of the heated head by the disk. These temperature fluctuations are reflected in the signal from the head as a thermoresistive signal comprising modulation of a baseline voltage level. The shock detection circuitry compares positive and negative excursions of this thermoresistive signal with a predetermined threshold voltage level. When the threshold is exceeded, indicating an external shock or vibration in excess of an allowable limit, writing of data is inhibited.Type: GrantFiled: June 13, 1996Date of Patent: July 7, 1998Assignee: International Business Machines CorporationInventors: Prakash Kasiraj, Steven Wayne Meeks, Timothy Clark Reiley
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Patent number: 5293116Abstract: At the wafer level, a conventional write signal is applied to a pre-selected thin film head. Thereafter, first and second constant amplitude, differing frequency sine wave signals are applied to the head along with a DC bias signal whose magnitude is varied. The level of frequency mixing in the output signal of the head is detected at each level of magnitude of the DC bias signal and this data is utilized in predicting the level of noise in the read-back signal of the thin film head during normal read and write operations in connection with a rotating storage disk.Type: GrantFiled: May 8, 1992Date of Patent: March 8, 1994Inventors: Donald E. Horne, Prakash Kasiraj, Fior D. Sargent