The invention relates generally to magnetic recording devices and specifically to a system and a method for using a magnetoresistive head within an integrated magnetic memory device.
The magnetoresistive sensors in use today are capable of spatial resolution only in the order of magnitude of their size. A typical sensor may be comprised of a single sensing element, or may comprise a large number of discrete sensing elements which are individually controlled and accessed by the system. The need to access the sensor elements individually poses limitations on the areal density in MRAM devices. In magnetoresistive (MR) heads, the trackwidth is ultimately determined by the length of the sensor element, which, for several reasons, cannot be reduced sufficiently to take full advantage of the modern magnetic storage media. Conventional magnetic memory recording techniques, devices, and sensors are discussed in the following references, hereby incorporated by reference:
1. H. Neal Bertram, Theory of Magnetic Recording, Cambridge: Cambridge University Press, 1994
2. Richard P. Feynman, Robert B. Leighton, Matthew Sands, The Feynman Lectures on Physics, vol.2, Moscow: Mir, 1966
3. M. I. Kaganov, V. M. Tsukernik, Priroda Magnetizma, Moscow: Nauka, 1982
4. John C. Mallinson, The Foundations of Magnetic Recording, San Diego: Academic Press, 1987
5. C. Denis Mee, Eric D. Daniel, Magnetic Recording Technology, McGraw-Hill, 1996
6. M. Prutton, Thin Ferromagnetic Films, Washington, Butterworths, 1964
7. Karlheinz Seeger, Semiconductor Physics, An Introduction, Berlin: Springer-Verlag, 1985
8. Ronald F. Soohoo, Magnetic Thin Films, New York: Harper and Row, 1965
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11. Hans Boeve, Christophe Bruynseraede, Jo Das, Kristof Dessein, Gustaaf Borghs, Jo De Boeck, xe2x80x9cTechnology assessment for the implementation of magnetoresistive elements with semiconductor components in magnetic random access memory (MRAM) architecturesxe2x80x9d, IEEE Trans. Magn. 35 (5), 2820 (1999)
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The invention addresses these goals. In one embodiment the invention includes a novel method of enhancing or suppressing the sensitivity of a part of magnetoresistive film area in a sensor by applying an external control field (to follow convention, we will use the term bias for a uniform external field, which is not applicable in this case). The response of the saturated part is significantly suppressed. Then, for example, expanding the saturated zone while monitoring the sensor response will allow us to scan the magnetization of the storage medium. The medium may be scanned with a single spot of saturation in the MR sensor film plane or, conversely, most of the film may be saturated, leaving one spot unaffected. In this manner no moving parts are necessary to perform the scan of the storage medium.
In another embodiment, the invention comprises a data storage device comprising: a magnetic storage medium; a magnetoresistive element; and, means, operatively coupled to said magnetoresistive element, for selectively controlling the sensitivity of a selected region of said magnetoresistive element to the magnetic field presented by the magnetic storage medium.
In a further embodiment, the invention comprises a data storage device comprising: a magnetic storage medium; a magnetoresistive element, the location of said magnetoresistive element being fixed relative to said magnetic storage medium; and, means, operatively coupled to said magnetoresistive element, for selectively controlling the sensitivity of a selected region of said magnetoresistive element to the magnetic field presented by a corresponding region of the magnetic storage medium wherein said corresponding region of the magnetic storage medium comprises a plurality of data storage locations.
In a further embodiment, the invention comprises a method for reading information stored on a magnetic storage medium with a magnetoresistive element, comprising the steps of: (a) altering the sensitivity of a selected region within the magnetoresistive element to an incident magnetic field; and, (b) reading information stored on the magnetic storage medium by sensing the effect of the incident magnetic field on the selected region of the magnetoresistive element.