Tai H Min, Age 624300 Mackin Woods Ln, San Jose, CA 95135

6351355, Feb 26, 2002

Feb 9, 1999

09/247814

Tai Min - San Jose CA
Yiming Huai - Pleasanton CA
Wengie Chen - Cupertino CA

Read-Rite Corporation - Fremont CA

G11B 5127

36032411, 36032412

The present invention provides spin valve with a magnetic compensation field which couples to the pinned layer and counteracts sensing current induced magnetic field. The spin valve sensor of the present invention may be formed having a structure comprising: a free layer, a first spacer layer, a pinned layer, a pinning layer, a second spacer layer, and a compensation layer. The compensation layer may be formed of ferromagnetic material with its magnetization set so that the compensation field oriented in a reinforcing relationship with the magnetization of the pinned layer. Current through the compensation layer and the spacer layer may add to the compensation field. The spacer layer may be formed of a nonmagnetic material of sufficient thickness to prevent interaction between the pinning layer and the compensation layer while providing a sufficiently small distance to allow sufficient magnetic coupling to the pinned layer. The present invention may be used to improve thermal stability and reduce Barkhausen noise while not impacting output symmetry.

6358635, Mar 19, 2002

Dec 20, 1999

09/467138

Tai Min - San Jose CA
Otto Voegeli - Morgan Hill CA
Rongfu Xiao - Fremont CA
Po-Kang Wang - San Jose CA

Headway Technologies, Inc. - Milpitas CA

G11B 566

428692, 428694 R, 428694 TM, 428694 TS, 428336, 428900, 360113

A magnetic shielding element for a magnetic recording and sensing device which prevents the problem of pop-corn noise or covariance of amplitude noise in the magnetic sensing device. The shielding element has a layer of antiferromagnetic exchange material formed on a layer of single domain first ferromagnetic material. The single domain first ferromagnetic material is stabilized by the antiferromagnetic exchange material. A layer of non-magnetic metal is then formed on the layer of antiferromagnetic exchange material and a layer of second ferromagnetic material is formed on the layer of non-magnetic metal to complete the shielding element. When the single domains of the first ferromagnetic material are disturbed by the strong magnetic fields of a write cycle they relax with a relaxation time of pico seconds and are fully relaxed before a read cycle begins. The fully relaxed layer of first ferromagnetic material then shields the magnetic sensing device from magnetic field fluctuations caused by the slower relaxation of the domains in the layer of second ferromagnetic material during a read cycle.

6385017, May 7, 2002

Sep 30, 1999

09/408492

Tai Min - San Jose CA
Po-Kang Wang - San Jose CA
Moris Musa Dover - San Jose CA

Headway Technologies, Inc. - Milpitas CA

G11B 5127

36032412, 36032731

A spin valve device comprises a free layer, a spacer layer, a pinned layer, an antiferromagnetic layer, and a patterned underlayer that includes a magnetic material for providing trackwidth and longitudinal bias. The patterned underlayer can comprise a buffer layer, an antiferromagnetic layer and a ferromagnetic layer. Alternatively, the patterned underlayer can comprises a buffer layer, a chromium layer and a hard biasing, permanent magnetic layer which provides trackwidth and longitudinal bias. A lower conductor can be located on the underlayer.

6606782, Aug 19, 2003

Mar 22, 2002

10/104778

Tai Min - San Jose CA
Po-Kang Wang - San Jose CA
Moris Musa Dovek - San Jose CA

Headway Technologies, Inc. - Milpitas CA

G11B 539

2960315, 2960314, 2960318, 2960307, 216 22, 216 40, 3603241, 36032411

To form a spin valve device, start by forming a gap layer. Form a buffer layer with a layer of refractory material on the buffer layer. Form patterned underlayers including a magnetic material for providing trackwidth and longitudinal bias on the buffer layer comprising either a lower antiferromagnetic layer stacked with a ferromagnetic layer or a Cr layer stacked with a permanent magnetic layer. Form an inwardly tapered depression in the patterned underlayers down to the buffer layer by either ion milling through a mask or a stencil lift off technique. Form layers covering the patterned underlayers that cover the inwardly tapered depression. Form free, pinned, spacer and antiferromagnetic layers. Form conductors either on a surface of the antiferromagnetic layer aside from the depression or between the buffer layer and the patterned underlayers.

6760966, Jul 13, 2004

Apr 30, 2002

10/135097

Po Kang Wang - San Jose CA
Moris Dovek - San Jose CA
Jibin Geng - Milpitas CA
Tai Min - San Jose CA

Headway Technologies, Inc. - Milpitas CA

G11B 5147

2960314, 2960313, 2960307, 36032412, 360322, 427128, 427131, 148108

As track density requirements for disk drives have grown more aggressive, GMR devices have been pushed to narrower track widths to match the track pitch of the drive width. Narrower track widths degrade stability, cause amplitude loss, due to the field originating from the hard bias structure, and side reading. This problem has been overcome in a process of manufacturing a device by adding an additional layer of soft magnetic material above the hard bias layers. The added layer provides flux closure to the hard bias layers thereby preventing flux leakage into the gap region. A non-magnetic layer must be included to prevent exchange coupling to the hard bias layers. In at least one embodiment the conductive leads are used to accomplish this.

6779248, Aug 24, 2004

Mar 7, 2002

10/093107

Moris M. Dovek - San Jose CA
Tai Min - San Jose CA

Headway Technologies, Inc. - Milpitas CA

G11B 5187

2960308, 2960307, 2960313, 2960314, 296032, 360322, 3603241, 36032411, 36032412, 148108, 148121

In bottom spin valves of the lead overlay type the longitudinal bias field that stabilizes the device tends to fall off well before the gap is reached. This problem has been overcome by providing a manufacturing process that includes inserting an additional antiferromagnetic layer between the hard bias plugs and the overlaid leads. This additional antiferromagnetic layer and the lead layer are etched in the same operation to define the read gap, eliminating the possibility of misalignment between them. The extra antiferromagnetic layer is also longitudinally biased so there is no falloff in bias strength before the edge of the gap is reached. A process for manufacturing the device is also described.

6929957, Aug 16, 2005

Sep 12, 2003

10/661039

Tai Min - San Jose CA, US
Po Kang Wang - San Jose CA, US

Headway Technologies, Inc. - Milpitas CA

H01L021/00

438 3, 438595, 438737

A magnetic tunneling junction (MTJ) memory cell and an MRAM array of such cells, is shielded by magnetic shields of ferromagnetic material or by ferromagnetic shields that are stabilized by patterned layers of antiferromagnetic material or permanent magnetic material. The ferromagnetic portions of the shields surround the MTJ cells substantially conformally and thereby can compensate the poles of the free layers of MTJ cells of various geometric cross-sectional shapes and also protect the cells from the adverse effects of extraneous fields. The additional antiferromagnetic and permanent magnetic materials stabilize the shields by exchange or direct coupling.

6943040, Sep 13, 2005

Aug 28, 2003

10/650600

Tai Min - San Jose CA, US
Po Kang Wang - Milpitas CA, US

Headway Technologes, Inc. - Milpitas CA

H01L021/00

438 3, 365 55, 365 66, 365171, 365173, 3652255, 36523003, 438673

A magnetic tunneling junction (MTJ) memory cell for a magnetic random access memory (MRAM) array is formed as a chain of magnetostatically coupled segments. The segments can be circular, elliptical, lozenge shaped or shaped in other geometrical forms. Unlike the isolated cells of typical MTJ designs which exhibit curling of the magnetization at the cell ends and uncompensated pole structures, the present multi-segmented design, with the segments being magnetostatically coupled, undergoes magnetization switching at controlled nucleation sites by the fanning mode. As a result, the multi-segmented cells of the present invention are not subject to variations in switching fields due to shape irregularities and structural defects.