Home | Links | Contact Us | More About Intellectual Property | Bookmark

Search patents:

Home

Metal Working

Disk-drive-with-thermal-asperity-reduction-circuitry-using-a-magnetic-tunnel-junction-sensor

Magnetic recording medium

An object of the present invention is to provide a ferromagnetic metal thin film type of magnetic ...

Magneto-resistive head using flux guide

What is claimed is: 1. A separate type magneto-resistive head for magnetically reproducing an ...

Longitudinal magnetic recording media and magnetic memory units

As discussed above, it may be said that there have been strong demands for highly reliable magnetic ...

Thin-film recording medium with thin metal sublayer

The present invention includes, in one aspect, an improvement in a magnetic film recording medium ...

Process of making a magnetic recording medium

We claim: 1. A process for the manufacture of a magnetic recording medium by vacuum-depositing a ...

Magnetic recording disk and sputtering process and apparatus for producing same

The present invention provides a continuous production from a direct current planar magnetron ...

Method of forming thin-film recording medium

It is one general object of the invention to provide a thin film medium having high coercivity, ...

Longitudinal magnetic recording media with fine grain crystal magnetic layer

OF THE EMBODIMENTS The surface of a disk substrate of an aluminum alloy containing 4% by weight of ...

Magnetic recording medium comprising an underlayer and a cobalt samarium amorphous magnetic layer having a SmCo.sub.5 crystalline interface with the underlayer

The present invention pertains to a thin film media structure for high density longitudinal ...

Oxidation resistant low expansion superalloys

The embodiments of the invention in which an exclusive property or privilege is claimed are defined ...

Disk drive with thermal asperity reduction circuitry using a magnetic tunnel junction sensor

Details

Inventors: Gill, Hardayal Singh;
Assignee: International Business Machines Corporation (Armonk, NY)
Primary Examiner: Renner; Craig A.
Assistant Examiner: Castro; Angel
Attorney, Agent or Firm: Gill; William D.

A disk drive system having a magnetic tunnel junction (MTJ) sensor having two MTJ stacks between first and second shields and a common electrode disposed between the two MTJ stacks. A first sense current is provided to the first MTJ stack by the first shield and the common electrode and a second sense current is provided to the second MTJ stack by the second shield and the common electrode. The magnetization directions of the pinned layers of the first and second MTJ stacks are fixed perpendicular to the ABS and antiparallel with respect to each other so that the magnetoresistive signal generated due to an external field from a disk by the first MTJ stack differs in phase by 180.degree. with respect to the magnetoresistive signal generated due to the same external field by the second MTJ stack. The voltages developed across the two MTJ stacks (voltages due to the presence of thermal asperities and voltages due to the presence of data fields) are applied to the inputs of a differential amplifier for substantial elimination of the thermal asperity signal.

DETAILED DESCRIPTION It is an object of the present invention to disclose a magnetic tunnel junction (MTJ) sensor for substantially eliminating the thermal asperity phenomena in disk drives utilizing MTJ sensors.
It is another object of the present invention to disclose a method and means for detecting and substantially eliminating the thermal asperity phenomena in disk drives utilizing MTJ sensors.
These and other objects and advantages are attained in accordance with the principles of the present invention by a magnetic tunnel junction (MTJ) sensor having a first MTJ stack separated from a second MTJ stack by a common electrode.
Electrodes for providing sense current to the first MTJ stack and to the second MTJ stack are provided by a first shield and a second shield, respectively.
The first MTJ stack has a free layer separated from a pinned layer by a tunnel barrier layer.
An AFM layer adjacent to the pinned layer provides an exchange field to fix (pin) the magnetization of the pinned layer perpendicular to the ABS.
The magnetization of the free layer is oriented parallel to the ABS and is free to rotate in the presence of a signal magnetic field.
Similarly, the second MTJ stack has a free layer separated from a pinned layer by a tunnel barrier layer.
An AFM layer adjacent to the pinned layer provides an exchange field to fix (pin) the magnetization of the pinned layer perpendicular to the ABS and antiparallel to the magnetization direction of the pinned layer of the first MTJ stack.
The magnetization of the free layer is oriented parallel to the ABS and is free to rotate in the presence of a signal magnetic field.
With the magnetizations of the pinned layers of the two MTJ stacks fixed perpendicular to the ABS and antiparallel with respect to each other, the magnetoresistive signal generated due to an external field from the disk by the first MTJ stack will differ in phase by 180.
degree.
with respect to the magnetoresistive signal generated due to the same external field by the second MTJ stack

Related patents

	Zero-voltage switched FM-PWM converter A variable-frequency pulse-width-modulated boost converter is provided which allows for operation at very high frequencies with minimal transient turn-on losses. A ...
	Current-limiting circuit In order to achieve the above objectives, the present invention provides a current-limiting circuit in which first and second main terminals of a main semiconductor ...
	Transient over voltage protection circuit for electrical power converters Broadly stated, the present invention comprises an overvoltage detection circuit that partially opens a normally closed switch connected between a rectifier circuit and ...
	Short circuit protection for power factor correction circuit The present invention accomplishes the desired result by monitoring not the power MOSFET current itself, but rather the relationship between the input voltage and the ...
	Power mosfet having current detection means Accordingly, it is an object of the present invention to provide a power MOSFET device which has overcome the above mentioned defects of the conventional ones. Another ...
	Soft-start switch with voltage regulation and current limiting An advantage of the present invention is a soft-start switch with regulation of voltage drop across the soft-start switch, i.e., V.sub.0 -V.sub.out, so that load sharing ...
	Apparatus and method for digital control of a power converter current OF THE PREFERRED EMBODIMENT While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the ...
	DC-to-DC converter capable of preventing overvoltages The present invention has an object to provide a compact synchronous rectification mode voltage drop type DC/DC converter with a high converting efficiency. Concretely ...
	Protected telecommunication test adapter module The problems with the prior art are overcome by the test adapter of the present invention. The present invention is a telecommunications test adapter that is modular, ...
	Recording system having head transducers with controlled skew OF THE PREFERRED EMBODIMENT The invention is best understood by reference to the figures wherein like parts are designated with like numerals throughout. One presently ...

0.004
Archive: All patents - Links Copyright (c)2006 Eipa-patents.org - All rights reserved