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公开(公告)号：SG46731A1
公开(公告)日：1998-02-20
申请号：SG1996009674
申请日：1996-05-02
Applicant: IBM
Inventor： FONTANA ROBERT EDWARD JR , GURNEY BRUCE ALVIN , LIN TSANN , SPERIOSU VIRGIL SIMON , TSANG CHING HWA , WILHOIT DENNIS RICHARD
Abstract: A spin valve magnetoresistive (SVMR) sensor uses a laminated antiparallel (AP) pinned layer 70 in combination with an improved antiferromagnetic (AF) exchange biasing layer 57. The pinned layer comprises two ferromagnetic films 72, 74 separated by a nonmagnetic coupling film 73 such that the magnetizations of the two ferromagnetic films are strongly coupled together antiferromagnetically in an antiparallel orientation. This laminated AP pinned layer is magnetically rigid in the small field excitations required to rotate the SVMR sensor's free layer. When the magnetic moments of the two ferromagnetic layers in this AP pinned layer are nearly the same, the net magnetic moment of the pinned layer is small. However, the exchange field is correspondingly large because it is inversely proportional to the net magnetic moment. The laminated AP pinned layer has its magnetization fixed or pinned by an AF material that is highly corrosion resistant but that has an exchange anisotropy too low to be usable in conventional SVMR sensors. In the preferred embodiment the AF layer is nickel-oxide and is formed on one of the magnetoresistive (MR) shields that serves as the substrate 45. Thus the AF material also serves as the insulating MR gap material. The location of the AF layer and the laminated AP-pinned layer to which it is exchange coupled on the bottom of the SVMR sensor allows for improved longitudinal biasing of the free layer when the SVMR sensor is fabricated.
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公开(公告)号：SG42860A1
公开(公告)日：1997-10-17
申请号：SG1996000225
申请日：1992-01-07
Applicant: IBM
Inventor： TANG YAW SHING , TSANG CHING HWA
IPC: G11B5/09 , G11B7/00 , G11B7/0045 , G11B7/0055 , G11B20/10
Abstract: A method and device for use in measurement and compensation of non-linear bitshift in non-linear communication media such as magnetic and optical recording devices. The method and device are based on special bit patterns constructed to eliminate at least one harmonic of the fundamental frequency of the data pattern if all bits are communicated without any non-linear bitshift. The presence of non-linear bitshift is manifested by the appearance of the harmonic. By measuring the magnitude of the harmonic, the amount of non-linear bitshift is determined, and compensation adjustment is then used to offset its effect on the data detection scheme.
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公开(公告)号：CA2148964A1
公开(公告)日：1996-01-27
申请号：CA2148964
申请日：1995-05-09
Applicant: IBM
Inventor： FONTANA ROBERT EDWARD , LIN TSANN , TSANG CHING HWA
Abstract: An improved spin valve (SV) magnetoresistive element has its free ferromagnetic layer in the form of a central active region with defined edges and end regions that are contiguous with and abut the edges of the central active region. A layer of antiferromagnetic material, preferably a nickel-manganese (Ni-Mn) alloy, is formed on and in contact with the ferromagnetic material in the end regions for exchange coupling with the end regions to provide them with a longitudinal bias of their magnetizations. The pinned ferromagnetic layer in the SV element is pinned by exchange coupling with a different layer of antiferromagnetic material, preferably an iron-manganese (Fe-Mn) alloy. This material has a substantially different Neel temperature from that of the antiferromagnetic material on the end regions. The process for making the SV element includes heating to different predetermined temperatures in the presence of an applied magnetic field to orient the magnetizations of the free and pinned layers in the proper direction. The SV element may be used as a sensor for reading data in magnetic recording systems.
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公开(公告)号：DE3783207D1
公开(公告)日：1993-02-04
申请号：DE3783207
申请日：1987-10-16
Applicant: IBM
Inventor： KROUNBI MOHAMAD TOWFIK , VOEGELI OTTO , TSANG CHING HWA
IPC: G11B5/39
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公开(公告)号：MY114962A
公开(公告)日：2003-02-28
申请号：MYPI9804348
申请日：1998-09-22
Applicant: IBM
Abstract: A MAGNETIC TUNNEL JUNCTION (MTJ) MAGNETORESISTIVE READ HEAD FOR A MAGNETIC RECORDING SYSTEM HAS THE MTJ SENSING OR FREE FERROMAGNETIC LAYER (132) ALSO FUNCTIONING AS A FLUX GUIDE TO DIRECT MAGNETIC RECORDING MEDIUM TO THE TUNNEL JUNCTION. THE MTJ FIXED FERROMAGNETIC LAYER (118) HAS ITS FRONT EDGE RECESSED FROM THE SENSING SURFACE (200) OF THE HEAD. BOTH THE FIXED AND FREE FERROMAGNETIC LAYERS ARE IN CONTACT WITH OPPOSITE SURFACES OF THE MTJ TUNNEL BARRIER LAYER (120) BUT THE FREE FERROMAGNETIC LAYER EXTENDS BEYOND THE BACK EDGE (208, 212) OF EITHER THE TUNNEL BARRIER LAYER OR THE FIXED FERROMAGNETIC LAYER, WHICHEVER BACK EDGE IS CLOSER TO THE SENSING SURFACE. THIS ASSURES THAT THE MAGNETIC FLUX IS NON-ZERO IN THE TUNNEL JUNCTION REGION. THE MAGNETIZATION DIRECTION OF THE FIXED FERROMAGNETIC LAYER IS FIXED IN A DIRECTION GENERALLY PERPENDICULAR TO THE SENSING SURFACE AND THUS TO THE MAGNETIC RECORDING MEDIUM, PREFERABLY BY INTERFACIAL EXCHANGE COUPLING WITH AN ANTIFERROMAGNETIC LAYER. THE MAGNETIZATION DIRECTION OF THE FREE FERROMAGNETIC LAYER IS ALIGNED IN A DIRECTION GENERALLY PARALLEL TO THE SURFACE OF THE MEDIUM IN THE ABSENCE OF AN APPLIED MAGNETIC FIELD AND IS FREE TO ROTATE IN THE PRESENCE OF APPLIED MAGNETIC FIELDS FROM THE MEDIUM. A LAYER OF HIGH COERCIVITY HARD MAGNETIC MATERIAL ADJACENT THE SIDES OF THE FREE FERROMAGNETIC LAYER LONGITUDINALLY BIASES THE MAGNETIZATION OF THE FREE FERROMAGNETIC LAYER IN THE PREFERRED DIRECTION.
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Patent Agency Ranking
公开(公告)号：DE69611326T2
公开(公告)日：2001-05-31
申请号：DE69611326
申请日：1996-06-13
Applicant: IBM
Inventor： FONTANA JR , GURNEY BRUCE ALVIN , LIN TSANN , SPERIOSU VIRGIL SIMON , TSANG CHING HWA , WILHOIT DENNIS RICHARD
Abstract: A spin valve magnetoresistive (SVMR) sensor uses a laminated antiparallel (AP) pinned layer 70 in combination with an improved antiferromagnetic (AF) exchange biasing layer 57. The pinned layer comprises two ferromagnetic films 72, 74 separated by a nonmagnetic coupling film 73 such that the magnetizations of the two ferromagnetic films are strongly coupled together antiferromagnetically in an antiparallel orientation. This laminated AP pinned layer is magnetically rigid in the small field excitations required to rotate the SVMR sensor's free layer. When the magnetic moments of the two ferromagnetic layers in this AP pinned layer are nearly the same, the net magnetic moment of the pinned layer is small. However, the exchange field is correspondingly large because it is inversely proportional to the net magnetic moment. The laminated AP pinned layer has its magnetization fixed or pinned by an AF material that is highly corrosion resistant but that has an exchange anisotropy too low to be usable in conventional SVMR sensors. In the preferred embodiment the AF layer is nickel-oxide and is formed on one of the magnetoresistive (MR) shields that serves as the substrate 45. Thus the AF material also serves as the insulating MR gap material. The location of the AF layer and the laminated AP-pinned layer to which it is exchange coupled on the bottom of the SVMR sensor allows for improved longitudinal biasing of the free layer when the SVMR sensor is fabricated.
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公开(公告)号：DE69611326D1
公开(公告)日：2001-02-01
申请号：DE69611326
申请日：1996-06-13
Applicant: IBM
Inventor： FONTANA JR , GURNEY BRUCE ALVIN , LIN TSANN , SPERIOSU VIRGIL SIMON , TSANG CHING HWA , WILHOIT DENNIS RICHARD
Abstract: A spin valve magnetoresistive (SVMR) sensor uses a laminated antiparallel (AP) pinned layer 70 in combination with an improved antiferromagnetic (AF) exchange biasing layer 57. The pinned layer comprises two ferromagnetic films 72, 74 separated by a nonmagnetic coupling film 73 such that the magnetizations of the two ferromagnetic films are strongly coupled together antiferromagnetically in an antiparallel orientation. This laminated AP pinned layer is magnetically rigid in the small field excitations required to rotate the SVMR sensor's free layer. When the magnetic moments of the two ferromagnetic layers in this AP pinned layer are nearly the same, the net magnetic moment of the pinned layer is small. However, the exchange field is correspondingly large because it is inversely proportional to the net magnetic moment. The laminated AP pinned layer has its magnetization fixed or pinned by an AF material that is highly corrosion resistant but that has an exchange anisotropy too low to be usable in conventional SVMR sensors. In the preferred embodiment the AF layer is nickel-oxide and is formed on one of the magnetoresistive (MR) shields that serves as the substrate 45. Thus the AF material also serves as the insulating MR gap material. The location of the AF layer and the laminated AP-pinned layer to which it is exchange coupled on the bottom of the SVMR sensor allows for improved longitudinal biasing of the free layer when the SVMR sensor is fabricated.
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公开(公告)号：DE69420789D1
公开(公告)日：1999-10-28
申请号：DE69420789
申请日：1994-07-04
Applicant: IBM
Inventor： CHEN MAO-MIN , FONTANA ROBERT EDWARD , KROUNBI MOHAMAD TOWFIK , KUNG KENNETH TING-YUAN , LEE JAMES HSI-TANG , LO JYH-SHLIEY JERRY , TSANG CHING HWA , WANG PO-KANG
IPC: G11B5/39
Abstract: A magnetoresistive (MR) read transducer is disclosed having passive end regions separated by a central active region in which an MR layer is formed over substantially only the central active region and in which a magnetic bias layer is formed in each passive end region. In one embodiment, each of the magnetic bias layers includes a layer of ferromagnetic material and a layer of antiferromagnetic material overlaying and in contact with the ferromagnetic layer to provide an exchange-coupled magnetic bias field. Alternatively a hard magnetic material is used to form the biasing layer. Each of the magnetic bias layers form an abutting junction having magnetic and electrical continuity with the MR layer to produce a stable longitudinal magnetic bias field in the transducer, even when the length of the active region is small to accommodate small track widths.
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公开(公告)号：SG67574A1
公开(公告)日：1999-09-21
申请号：SG1998004212
申请日：1998-10-15
Applicant: IBM
Inventor： DILL FREDERICK HAYES , FONTANA ROBERT EDWARD JR , PARKIN STUART STEPHEN PAPWORTH , TSANG CHING HWA
Abstract: A magnetic tunnel junction (MTJ) magnetoresistive read head for a magnetic recording system has the MTJ device (110,120,130) located between two spaced-apart magnetic shields (S1,S2). The magnetic shields, which allow the head to detect individual magnetic transitions from the magnetic recording medium without interference from neighboring transitions. also function as electrical leads for connection of the head to sense circuitry. Electrically conductive spacer layers (102,104) are located at the top and bottom of the MTJ device and connect the MTJ device to the shields. The thickness of the spacer layers is selected to optimize the spacing between the shields, which is a parameter that controls the linear resolution of the data that can be read from the magnetic recording medium. To reduce the likelihood of electrical shorting between the shields if the shield-to-shield spacing is too small, each of the shields can have a pedestal region (161,163) with the MTJ device located between the two pedestals, so that the shield-to-shield spacing outside the pedestal regions is greater than in the pedestal regions.
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公开(公告)号：DE69412660D1
公开(公告)日：1998-10-01
申请号：DE69412660
申请日：1994-01-12
Applicant: IBM
Inventor： KROUNBI MOHAMAD TOWFIK , KUNG KENNETH TING-YUAN , TSANG CHING HWA
Abstract: A magnetoresistive (MR) read transducer assembly has passive end regions 26 separated by a central active region 20. Layers of a first biasing material 14 and a nonmagnetic decoupling spacer material 16 are deposited on a substrate 12, then covered by a mask 18 only in the central region. By etching or ion milling, those parts of the layers not covered by the mask are removed to define a transverse biasing means in the central region and define the passive end regions. With the same mask remaining in place, a conductive material 22 and exchange layer 24 comprising a second biasing material are deposited over all regions. The mask is removed to define and provide conductor leads and longitudinal biasing means only in the end regions. MR material is thereafter deposited as a continuous thin film 28 in direct contact with the central region containing the transverse biasing means and in direct contact with the end regions containing the longitudinal biasing means. This fabrication technique has no critical etching steps requiring stopping at or near a particular interface and the MR film provides a continuous platform for carrying current without butted junctions in the current path.
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