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1.发明专利
公开(公告)号：SG82614A1
公开(公告)日：2001-08-21
申请号：SG1999002429
申请日：1999-05-13
Applicant: IBM
Abstract: A magnetic tunnel junction magnetoresistive read head has one fixed ferromagnetic layer and one generally rectangularly shaped sensing ferromagnetic layer on opposite sides of the tunnel barrier layer, and a biasing ferromagnetic layer located around the side edges and back edges of the sensing ferromagnetic layer. An electrically insulating layer separates the biasing layer from the edges of the sensing layer. The biasing layer is a continuous boundary biasing layer that has side regions and a back region to surround the three edges of the sensing layer. When the biasing layer is a single layer with contiguous side and back regions its magnetic moment can be selected to make an angle with the long edges of the sensing layer. In this manner the biasing layer provides both a transverse bias field to compensate for transverse ferromagnetic coupling and magnetostatic coupling fields acting on the sensing layer to thus provide for a linear response of the head and a longitudinal bias field to stabilize the head. The biasing layer may also be formed with discrete side regions and a back region. The discrete side regions may have a magnetic moment oriented in a different direction from the moment of the back region in order to provide the correct combination of transverse and longitudinal bias fields.
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公开(公告)号：SG42330A1
公开(公告)日：1997-08-15
申请号：SG1996000779
申请日：1993-11-15
Applicant: IBM
Abstract: A magnetoresistive sensor based on the spin valve effect in which a component of the read element resistance varies as the cosine of the angle between the magnetization directions in two adjacent magnetic layers is described. The sensor read element includes two adjacent ferromagnetic layers separated by a non-magnetic metallic layer, the magnetic easy axis of each of the ferromagnetic layers being aligned along the longitudinal axis of the ferromagnetic layers and perpendicular to the trackwidth of an adjacent magnetic storage medium. The sense current flowing in the sensor element generates a bias field which sets the direction of magnetization in each ferromagnetic layer at an equal, but opposite, angle theta with respect to the magnetic easy axis thus providing an angular separation of 2 theta in the absence of an applied magnetic signal. The magnetizations of both ferromagnetic layers are responsive to an applied magnetic field to change their angular separation by an amount 2 delta theta .
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公开(公告)号：SG44438A1
公开(公告)日：1997-12-19
申请号：SG1996000392
申请日：1993-12-17
Applicant: IBM
Inventor： FONTANA ROBERT EDWARD JR , THOMPSON DAVID A , WILLIAMS MASON LAMAR III , YEACK-SCRANTON CELIA ELIZABETH
Abstract: A unitary magnetic transducer and suspension assembly suitable for use in both contact recording and in winchester-type applications is described. A generally rectangular elongate flat suspension member includes a ring-type inductive read/write transducer formed integrally with the suspension member and is embedded in one end of the suspension member. The ring-type inductive transducer is suitable for horizontal recording applications. The transducer magnetic poletips and magnetic gap are formed and positioned such that the poletips and gap are essentially co-planar with the air bearing surface of a slider-shaped protrusion extending from the lower surface of the end of the suspension member adjacent a moving media during operation. The air bearing surface presented to the disk has most of its area covered with a wear layer to minimize wear of the slider surface and poletips.
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公开(公告)号：AU1788295A
公开(公告)日：1996-05-09
申请号：AU1788295
申请日：1995-05-04
Applicant: IBM
Inventor： DOVEK MORIS MUSA , FONTANA ROBERT EDWARD JR , SPERIOSU VIRGIL SIMON , SPONG JAQUELIN KETNER
Abstract: A magnetic field sensor (10) uses four individual magnetoresistive spin valve elements (A,B,C,D) electrically connected in a bridge circuit. The spin valve elements (A,B,C,D) are lithographically formed on the same substrate with their free layers (36) having their magnetization axes parallel to one another. An electrically conductive fixing layer is formed on the substrate but is insulated from the spin valve elements. The application of current through the fixing conductor during fabrication of the field sensor fixes the direction of magnetization of two of the pinned layers (39) to be antiparallel to the direction of magnetization of the other two pinned layers (39). The bridge circuit (10) output voltage is responsive to an external magnetic field (4) in the plane of the sensor (10). By appropriate fixing of the direction of magnetization of the pinned layers (39) during sensor (10) fabrication, and appropriate connection to the input (20,22) and output leads (24,26), the bridge circuit output voltage is a measure of either the magnetic field or field gradient.
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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：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：SG60136A1
公开(公告)日：1999-02-22
申请号：SG1997003873
申请日：1997-10-27
Applicant: IBM
Abstract: A magnetic tunnel junction device for use as a magnetic memory cell or a magnetic field sensor has one fixed ferromagnetic layer and one sensing ferromagnetic layer formed on opposite sides of the insulating tunnel barrier layer, and a hard biasing ferromagnetic layer that is electrically insulated from but yet magnetostatically coupled with the sensing ferromagnetic layer. The magnetic tunnel junction in the device is formed on an electrical lead on a substrate and is made up of a stack of layers. The layers in the stack are an antiferromagnetic layer, a fixed ferromagnetic layer exchange biased with the antfferromagnetic layer so that its magnetic moment cannot rotate in the presence of an applied magnetic field, an insulating tunnel barrier layer in contact with the fixed ferromagnetic layer, and a sensing ferromagnetic layer in contact with the tunnel barrier layer and whose magnetic moment is free to rotate in the presence of an applied magnetic field. The stack is generally rectangularly shaped with parallel side edges. A layer of hard biasing ferromagnetic material is located near to but spaced from the side edges of the sensing ferromagnetic layer to longitudinally bias the magnetic moment of the sensing ferromagnetic layer in a preferred direction. A layer of electrically insulating material isolates the hard biasing material from the electrical lead and the sensing ferromagnetic layer so that sense current is not shunted to the hard biasing material but is allowed to flow perpendicularly through the layers in the stack.
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公开(公告)号：DE68909462T2
公开(公告)日：1994-05-11
申请号：DE68909462
申请日：1989-02-15
Applicant: IBM
IPC: G11B5/39
Abstract: In a magnetoresistive (MR) read transducer comprising a thin MR film (10) formed of ferromagnetic material and a thin nonmagnetic spacer film layer (14) in contact with the MR film, the spacer film (14) comprises a material selected from the group consisting of nichrome and nichrome with chromium oxide. To make such a transducer, a thin soft magnetic material film is deposited in contact with the spacer film so that a transverse bias is produced in at least a part of the MR film. The resistivity of the spacer film can be chosen by selecting the ratio of nichrome to chromium oxide in the spacer film. In a specific embodiment (Fig. 2) the spacer film (24) extends over only the central region of the MR film (10). Where the MR film consists of a nickel based alloy, a wet chemical etching process using an etchant comprising an aqueous solution of ceric ammonium nitrate and acetic acid can be used to pattern the spacer film.
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公开(公告)号：DE68909462D1
公开(公告)日：1993-11-04
申请号：DE68909462
申请日：1989-02-15
Applicant: IBM
IPC: G11B5/39
Abstract: In a magnetoresistive (MR) read transducer comprising a thin MR film (10) formed of ferromagnetic material and a thin nonmagnetic spacer film layer (14) in contact with the MR film, the spacer film (14) comprises a material selected from the group consisting of nichrome and nichrome with chromium oxide. To make such a transducer, a thin soft magnetic material film is deposited in contact with the spacer film so that a transverse bias is produced in at least a part of the MR film. The resistivity of the spacer film can be chosen by selecting the ratio of nichrome to chromium oxide in the spacer film. In a specific embodiment (Fig. 2) the spacer film (24) extends over only the central region of the MR film (10). Where the MR film consists of a nickel based alloy, a wet chemical etching process using an etchant comprising an aqueous solution of ceric ammonium nitrate and acetic acid can be used to pattern the spacer film.
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公开(公告)号：SG67573A1
公开(公告)日：1999-09-21
申请号：SG1998004207
申请日：1998-10-14
Applicant: IBM
Abstract: A magnetic tunnel junction (MTJ) magnetoresistive read head for a magnetic recording system has the MTJ sensing or free ferromagnetic layer also functioning as a flux guide to direct magnetic flux from the magnetic recording medium to the tunnel junction. The MTJ fixed ferromagnetic layer has its front edge recessed from the sensing surface of the head. Both the fixed and free ferromagnetic layers are in contact with opposite surfaces of the MTJ tunnel barrier layer but the free ferromagnetic layer extends beyond the back edge 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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