International Business Machines Corporation

Joseph Adam Aboaf

Vincent N Kahwaty

Edward V Denison

Erik Klokholm

Jules David Friedman

Robert W Broadie

H Bernhard Pogge

Gerald Steving

Herman Carl Kluge, Ii

Edward Virgil Dennison

Edward M Hull

David John Seagle

Mohamad Towfik Krounbi

Jerome J Cuomo

James Lamar Nix

Frank B Shelledy

William A Pliskin

Thomas R McGuire

Thomas J Beaulieu

Amitava Gangulee

Vincent Noel Kahwaty, Deceased

Robert J Kobliska

Sigrid R Herd

Herman C Kluge

A multi-element read-write magnetic recording head for recording information on a magnetic tape and for reading recorded information therefrom is provided. The recording head comprises an equal number of associated read elements and write elements to form a two-gap recording head comprising pairs of read and write elements. The two-gap recording head further comprises a first module and a second module, the first and second modules each comprising a plurality of read and write head elements. A first group of read and write heads is configured to perform in a forward direction of movement of the magnetic tape and a second group of read and write heads is configured to perform in a reverse direction of movement of the magnetic tape. One of the modules contains an equal number of forward read heads and reverse write heads and the other of the modules contains an equal number of reverse read heads and forward write heads, to provide decoupling of reading and writing functions and to enable servoing by a given read element of a write element associated therewith. Asymmetry of the magnetic recording head is provided by offsetting leads to the read elements in a given module from leads to said write elements in the same module, while maintaining orthogonality between read and write element leads near the read and write elements. The asymmetry minimizes both inductive and capacitive feedthrough into adjacent readers. As a consequence, noise produced during the writing process is reduced, providing an improved signal-to-noise ratio and thereby permitting same gap servoing.

Asymmetric recording head for same gap servo optimization

A thin-film magnetic head includes a substrate having first and second magnetic layers disposed above the substrate and formed as a laminated sequence of magnetic sub-layers. The first and second magnetic layers have corresponding first ends representing a pole tip region of the head, corresponding second ends representing a back gap region of the head, and corresponding intermediate portions representing an intermediate region of the head between the pole tip region and the back gap region. The first and second magnetic layers are joined together in physical contact at the back gap region and are spaced from one another at the pole tip region and at the intermediate region. A nonmagnetic gap layer is disposed between the first and second magnetic layers at the pole tip region. A magnetic coil structure is disposed between the first and second magnetic layers at the intermediate region. The second magnetic layer has a sloped region wherein the second magnetic layer slopes away from the first magnetic layer behind the pole tip region to form a space for the magnetic coil structure. The sloped region of the second magnetic layer may have less magnetic permeability than other portions of the second magnetic layer. A third magnetic layer is thus disposed on the second magnetic layer and extends from the back gap region to cover at least the sloped region of the second magnetic layer.

Dual header tape head design

A magneto-resistive read/write tape head is provided for reading and writing to tape media along a tape head face. The tape head comprises a plurality of modules, each module comprising a read element and a write element spaced apart and terminating at the tape head face and formed over a substrate. The read element comprises a soft film bias layer and a hard film bias layer butted against the SFB layer. The write element comprises two pole tips spaced apart by a gap. The tape head further includes a plurality of activating conducting coil turns operatively associated with the write element and covered by a cross-linked photoresist and positioned between the gap and one of the pole tips and set back from the tape head face. The tape head has at least one of the following elements: (a) a wear shield between the read element and the write element for limiting wear of the gap between the two pole tips, the wear shield being grounded for decoupling read and write functions of the tape head, for allowing same module read/servo/write functions simultaneously, and for grounding static charge from the tape media; (b) a layer of electrically conductive and corrosion-resis tant material, such as rhodium, under the hard film bias layer to reduce its resistance; and (c) a non-activating dummy coil turn closer to the pole tips than the activating coil turns for defining a forward termination of the cross-linked photoresist between the activating coil turns and the tape head face to thereby provide improved ease of processability.

Piggyback magneto-resistive read/write tape head with optimized process

A magnetoresistive sensor design and fabrication process that provides improved microtrack profile linearity for servo elements while simultaneously providing stable and linear data sensing elements suitable for high density tape head applications. The stability and uniformity of both data and servo sensor elements is enhanced through the use of a grating profile under both the soft film biased magnetoresistive sensor layer and the hard bias stabilizing magnets. Processing steps are eliminated by replicating the grating pattern for the servo sensor elements through a thick layer of alumina or silicon dioxide. The outer read shield is removed from the servo elements using a stripping process that eliminates structural damage arising from alumina pinhole's. Both element types are free of significant Barkhausen noise and instability because of the grating-stabilized domains in both the active magnetoresistive regions and the passive hard-biasing regions of each sensor. Each servo sensor is disposed at a greater distance from the single shield to optimize the microtrack profile. The resulting reduction in servo sensor frequency response leaves sufficient bandwidth for precise servo positioning.

Method of making magnetoresistive sensor with improved microtrack

A magnetoresistive sensor design and fabrication process that provides improved microtrack profile linearity for servo elements while simultaneously providing stable and linear data sensing elements suitable for high density tape head applications. The stability and uniformity of both data and servo sensor elements is enhanced through the use of a grating profile under both the soft film biased magnetoresistive sensor layer and the hard bias stabilizing magnets. Processing steps are eliminated by replicating the grating pattern for the servo sensor elements through a thick layer of alumina or silicon dioxide. The outer read shield is removed from the servo elements using a stripping process that eliminates structural damage arising from alumina pinholes. Both element types are free of significant Barkhausen noise and instability because of the grating-stabilized domains in both the active magnetoresistive regions and the passive hard-biasing regions of each sensor. Each servo sensor is disposed at a greater distance from the single shield to optimize the microtrack profile. The resulting reduction in servo sensor frequency response leaves sufficient bandwidth for precise servo positioning.

Hard-film stabilized soft-film biased magnetoresistive sensor with an

An arbitrary pattern write head assembly for writing timing-based servo patterns on magnetic storage media is provided, comprising: (a) a first pole piece comprising a substrate comprising a magnetic material, said substrate having a major surface; (b) a plurality of electrically conducting windings formed on the major surface; and (c) a second pole piece formed on the substrate, with a portion thereof formed above the plurality of electrically conducting windings and electrically insulated therefrom, the second pole piece having at least one opening therethrough defining a gap above the electrically conducting windings and the substrate, the second pole piece comprising at least two layers, each layer comprising a magnetic material. A method of batch fabricating servo writer heads is also provided for batch fabrication of servo writer heads at a very low cost. The method enables fabrication of heads capable of azimuthal recording commonly practiced in the video recording art. Hard nitrided Fe/NiFe poletip materials are used to minimize wear in tape head use.

Process for fabricating an arbitrary pattern write head

Arbitrary pattern write head assembly for writing timing-based servo

An interleaved bi-directional magnetic tape head for contact recording can have a poletip enhanced by providing a thin film of a soft magnetic material deposited onto a magnetic ferrite substrate. The second pole piece is a thin film of the soft magnetic material. A closure block of a non-magnetic ceramic encloses the layers together with leveling insulation layers and a deposited activating conductor turns. The stripe poletip deposited onto the magnetic ferrite extends for a distance just short of the first conductor turn and provides a balancing of the saturation moment of the pole pieces and provides for better recording capability, especially when operating in a trailing magnetic ferrite mode.

Magnetic head with magnetic substrate and an enhanced poletip thereon

An interleaved bi-directional magentic tape head for contact recording can have a poletip enhanced by providing a thin film of a soft magnetic material deposited onto a magnetic ferrite substrate. The second pole piece is a thin film of the soft magnetic material. A closure block of a non-magnetic ceramic encloses the layers together with leveling insulation layers and a deposited activating conductor turns. The stripe poletip deposited onto the magnetic ferrite extends for a distance just short of the first conductor turn and provides a balancing of the saturation moment of the pole pieces and provides for better recording capability, especially when operating in a trailing magnetic ferrite mode.

Method for making magnetic head with enhanced poletip

A soft film biased magnetoresistive sensor (10) is fabricated to have reduced Barkhausen noise. The magnetic ratio of the film layers (14 and 18) is controlled to be in the range of 1.7 to 1.95 and the optimum bias point is controlled to be in the range of 35 and 41 degrees.

Very low noise magnetoresistive sensor for high density media

Devices and circuits are described employing magnetoresistive materials exhibiting a negative .DELTA..rho. effect (.DELTA..rho.=.rho..parallel.-.rho..perp.). In these materials, the electrical resistivity .rho. of the material in a direction perpendicular to the direction of current through the material is greater than the electrical resistivity .rho..parallel. of the material in a direction parallel to the direction of the electrical current through the material. These are ferromagnetic materials exhibiting magnetoresistance in the presence of an electrical current through the material and a magnetic field applied to the material to magnetize it to saturation at room temperature. These devices and circuits have advantages over conventional devices and circuits employing magnetoresistive materials of the conventional type, in which .DELTA..rho. is a positive quantity.

New magnetoresistive materials

An alloy of Co.sub.x Pt.sub.y with y between 10 and 30 at. % is made by sputtering with H.sub.c &gt;500 Oe and 4.pi.M.sub.s &gt;5000 gauss, and zero magnetostriction. For 10 to 30 at. % Co the sputtered alloy has an H.sub.c of 500-1000 Oe with 4.pi.M.sub.s of 4000-14000 gauss, a magnetostriction passing through zero between 20 and 30 at. % of Pt. For thickness below 1000.ANG. H.sub.c is large (for the above range of alloys) and magnetization is also larger and coercivity varies as a direct function of Pt composition in the alloy up to 30 at. %.

Zero to low magnetostriction, high coercivity, polycrystalline, Co-Pt

A low or zero magnetostriction ferromagnetic alloy is used for a magnetic recording medium. The alloy is (Fe.sub.y Co.sub.1-y).sub.1-x Cr.sub.x where y (Fe) is preferably 15-23 atomic percent of the FeCo part of the alloy. The value of x (Cr) is 7-20 atomic percent of the alloy and the remainder 1-x (FeCo) is 83-92 atomic percent of the alloy. The maximum ranges of the composition of the alloy are about as follows:

Zero magnetostriction Fe-Co-Cr magnetic recording media

An amorphous alloy of cobalt and from about 14 to 30 atomic percent of titanium can be deposited upon a substrate by r.f. sputtering from 10 to 30 percent of titanium. The properties of the amrophous CoTi films are similar to those of transition metal-metalloid glasses in that they have soft magnetic properties (low H.sub.c) and their resistivity is in the 100-200 micro-ohm centimeter range. Unlike most metal-metalloid glasses, these films have very low magnetostriction and they are more stable to thermal annealing. They are more corrosion resistant than permalloy plated films. The films can be employed as magnetic yoke layers in magnetic recording heads or in the bubble propagation structures of bubble domain devices, as substitutes for 80:20 Ni:Fe alloys. The FeCoTi, NiCoTi and FeNiCoTi amorphous alloys have similar characteristics to the CoTi amorphous alloys for Ti concentrations on the order of 14 to 30 atomic percent where the ratio of Co to Fe and or Ni is greater than or equal to about 1 to 1.

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Tucson, AZ, United States of America

Joseph Adam Aboaf