Virgil Simon Speriosu

US Patent:

53412613, Aug 23, 1994

Filed:

Aug 26, 1991

Appl. No.:

7/750157

Inventors:

Bernard Dieny - Grenoble Cedex, FR
Bruce A. Gurney - Santa Clara CA
Stuart S. P. Parkin - San Jose CA
Ian L. Sanders - Morgan Hill CA
Virgil S. Speriosu - San Jose CA
Dennis R. Wilhoit - Morgan Hill CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5127

US Classification:

360113

Abstract:

A magnetoresistive (MR) sensor comprising a layered structure having at least one trilayer comprising a first and a second thin film ferromagnetic layers separated by and in interfacial contact with a third thin film non-metallic layer. A fourth thin film layer of material is within the first ferromagnetic layer, and the fourth layer has a thickness between a fraction of a monolayer and several monolayer and is located at predetermined distance from the interface between the first and third layers. A current flow is produced through the MR sensor and variations in resistivity of the MR sensor produced by rotation of the magnetization in one or both of the ferromagnetic layers is sensed as a function of the magnetic field being sensed.

US Patent:

55983081, Jan 28, 1997

Filed:

Aug 15, 1994

Appl. No.:

8/290324

Inventors:

Bernard Dieny - Grenoble Cedex, FR
Bruce A. Gurney - Santa Clara CA
Stuart S. P. Parkin - San Jose CA
Ian L. Sanders - Morgan Hill CA
Virgil S. Speriosu - San Jose CA
Dennis R. Wilhoit - Morgan Hill CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5127
G11B 533

US Classification:

360113

Abstract:

A magnetoresistive (MR) sensor comprising a layered structure having at least one trilayer comprising a first and a second thin film ferromagnetic layers separated by and in interfacial contact with a third thin film non-metallic magnetic layer. A fourth thin film layer of material is within the first ferromagnetic layer, and the fourth layer has a thickness between a fraction of a monolayer and several monolayers and is located at predetermined distance from the interface between the first and third layers. A current flow is produced through the MR sensor and variations in resistivity of the MR sensor produced by rotation of the magnetization in one or both of the ferromagnetic layers is sensed as a function of the magnetic field being sensed.

US Patent:

62399551, May 29, 2001

Filed:

Mar 30, 1999

Appl. No.:

9/280497

Inventors:

Moris Musa Dovek - San Carlos CA
Robert E. Fontana - San Jose CA
Richard Hsiao - San Jose CA
Mohamad Towfik Krounbi - San Jose CA
Hugo Alberto Emilio Santini - San Jose CA
Virgil Simon Speriosu - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 539

US Classification:

360321

Abstract:

The back end of an MR sensor and a flux guide are joined by a contiguous self-aligned junction so that a predictable overlap of the flux guide on the back end of the MR sensor can be achieved for optimizing signal flux density in the MR sensor. Lead/longitudinal bias layers for the MR sensor are also joined by a contiguous selfaligned junction to the flux guide for stabilizing the flux guide. By employing a single lift off resist mask the MR sensor and the lead/longitudinal bias layers can be patterned followed by deposition of the flux guide. The flux guide is a bilayer of an insulation material layer and a flux guide material layer. The insulation material layer is sandwiched between the MR sensor and the flux guide material layer and between the lead/longitudinal bias layers and the flux guide material layer. A heat guide or combined flux guide and heat guide may be substituted for the aforementioned flux guide.

US Patent:

53010795, Apr 5, 1994

Filed:

Nov 17, 1992

Appl. No.:

7/977382

Inventors:

William C. Cain - San Jose CA
Bernard Dieny - Grenoble Credex, FR
Robert E. Fontana - San Jose CA
Virgil S. Speriosu - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 530

US Classification:

360113

Abstract:

A magnetoresistive read 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.

US Patent:

56508875, Jul 22, 1997

Filed:

Feb 26, 1996

Appl. No.:

8/606625

Inventors:

Moris Musa Dovek - San Carlos CA
Bruce Alvin Gurney - Santa Clara CA
Virgil Simon Speriosu - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5455
G11B 539

US Classification:

360 75

Abstract:

Sensors based on the giant magnetoresistance effect, specifically "spin valve" (SV) magnetoresistive sensors, have applications as external magnetic field sensors and as read heads in magnetic recording systems, such as rigid disk drives. These sensors have a ferromagnetic layer whose magnetization orientation is fixed or pinned by being exchange coupled to an antiferromagnetic layer. The magnetization of the pinned layer will become misaligned and the sensor will experience an abnormal response to the field being sensed, i. e. , the external magnetic field or the recorded data in the magnetic media, if an adverse event elevates the antiferromagnetic layer above its blocking temperature. A pinned layer mangetization reset system is incorporated into systems that use SV sensors. The reset system generates an electrical current waveform that is directed through the SV sensor with an initial current value sufficient to heat the antiferromagnetic layer above its blocking temperature, and a subsequent lower current value to generate a magnetic field around the pinned layer sufficient to properly orient the magnetization of the pinned layer while the antiferromagnetic layer is cooling below its blocking temperature.

US Patent:

57012237, Dec 23, 1997

Filed:

Aug 23, 1996

Appl. No.:

8/697396

Inventors:

Robert Edward Fontana - San Jose CA
Bruce Alvin Gurney - Santa Clara CA
Tsann Lin - Saratoga CA
Virgil Simon Speriosu - San Jose CA
Ching Hwa Tsang - Sunnyvale CA
Dennis Richard Wilhoit - Morgan Hill CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 539

US Classification:

360113

Abstract:

A spin valve magnetoresistive (SVMR) sensor uses a laminated antiparallel (AP) pinned layer in combination with an improved antiferromagnetic (AF) exchange biasing layer. The pinned layer comprises two ferromagnetic films separated by a nonmagnetic coupling film 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.

US Patent:

61815322, Jan 30, 2001

Filed:

Mar 30, 1999

Appl. No.:

9/280489

Inventors:

Moris Musa Dovek - San Carlos CA
Robert E. Fontana - San Jose CA
Richard Hsiao - San Jose CA
Mohamad Towfik Krounbi - San Jose CA
Hugo Alberto Emilio Santini - San Jose CA
Virgil Simon Speriosu - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 539

US Classification:

360321

Abstract:

The back end of an MR sensor and a flux guide are joined by a contiguous self-aligned junction so that a predictable overlap of the flux guide on the back end of the MR sensor can be achieved for optimizing signal flux density in the MR sensor. Lead/longitudinal bias layers for the MR sensor are also joined by a contiguous self-aligned junction to the flux guide for stabilizing the flux guide. By employing a single lift off resist mask the MR sensor and the lead/longitudinal bias layers can be patterned followed by deposition of the flux guide. The flux guide is a bilayer of an insulation material layer and a flux guide material layer. The insulation material layer is sandwiched between the MR sensor and the flux guide material layer and between the lead/longitudinal bias layers and the flux guide material layer. A heat guide or combined flux guide and heat guide may be substituted for the aforementioned flux guide.

US Patent:

50141473, May 7, 1991

Filed:

Oct 31, 1989

Appl. No.:

7/429678

Inventors:

Stuart S. P. Parkin - San Jose CA
Kevin P. Roche - San Jose CA
Virgil S. Speriosu - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 539
G11B 530

US Classification:

360113

Abstract:

An improved thin film magnetoresistive (MR) sensor uses an alloy comprising Fe. sub. (1-x) Mn. sub. x, where x is within the range of 0. 3 to 0. 4, as an antiferromagnetic layer to provide longitudinal exchange bias in the ferromagnetic MR layer. In a specific embodiment the exchange bias is at a high level and is independent of thickness of the antiferromagnetic layer over a wide range.