Magnetic memory device

• US 6,438,025 B1
• Filed: 09/08/2000
• Issued: 08/20/2002
• Est. Priority Date: 09/08/1999
• Status: Expired due to Fees

• Current Assignee: Skarupo, Sergei
• Original Assignee: Skarupo, Sergei
• Inventors: Skarupo, Sergei
• Primary Examiner(s): Nguyen, Viet Q.
• Application Number:
  US09/658,766
• Time in Patent Office: 711 Days
• Field of Search: 365/158, 365/33, 365/63, 365/66, 365/67, 365/97, 365/99, 365/171, 365/209, 365/225.5
• US Class Current: 365/158
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11B 2005/0002 Special dispositions or recording techniques
• CPC Class Codes: G11B 2005/0005 Arrangements, methods or circuits
• CPC Class Codes: G11B 2005/0008 Magnetic conditionning of heads, e.g. biasing
• CPC Class Codes: G11B 2005/0013 of transducers, e.g. linearisation, equalisation
• CPC Class Codes: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11C 11/14 using thin-film elements
• CPC Class Codes: G11C 13/025 using fullerenes, e.g. C60, or nanotubes, e.g. carbon or silicon nanotubes
• CPC Class Codes: G11C 2213/81 Array wherein the array conductors, e.g. word lines, bit lines, are made of nanowires

Abstract

The invention described herein defines a system and a method for selectively controlling the sensitivity of a region of a magnetoresistive element to an incident magnetic field, by applying an external magnetic field to the magnetoresistive element. A number of applications to non-volatile data storage are described, as is a magnetic sweep element based on a FET structure. Finally, the storage media and recording modes (in-plane vs. perpendicular) best suited to the proposed applications are analyzed, and the desired or optimal characteristics of the proposed devices are discussed.

Claims

1. A data storage system for the storage and retrieval of data information, comprising:

a magnetic storage medium for storage of data;

a magnetosensitive sensor, proximate to said magnetic storage medium;

means for generating a spatially distributed control field within said magnetosensitive sensor to create a selected region having varied magnetic sensitivity; and

,

means for detecting a change in the properties of said magnetosensitive sensor to read the data stored by said magnetic storage medium.

2. The data storage system of claim 1, wherein said magnetosensitive sensor and said magnetic storage medium are in fixed positions with respect to one another.

3. The data storage system of claim 1, wherein said magnetosensitive sensor includes a magnetosensitive film, and further wherein said means for generating a spatially distributed control field includes a plurality of electrically conductive control wires, spatially distributed within a plane parallel to or coincident with the plane of said magnetosensitive film, whereupon a passing of an electric current through a set of said control wires generates a magnetic field in the vicinity of said set of control wires and changes the magnetic sensitivity of a corresponding region of said magnetosensitive film.

4. The data storage system of claim 3, wherein said means for generating includes a control circuit for selecting a set of said control wires through which to pass electric current.

5. The data storage system of claim 4, wherein the selected region of varied sensitivity may be moved within the magnetoresistive sensor by successively selecting different sets of control wires through which to pass electric current.

6. The data storage system of claim 1, wherein said selected region corresponds to a single data storage location of the storage medium.

7. The data storage system of claim 3, wherein said plurality of control wires forms a two-dimensional matrix of substantially orthogonal wires, wherein the portion of magnetosensitive film to be desensitized is selected by passing a current through a set of two or more control wires, including at least one wire in each direction of said matrix.

8. The data storage system of claim 7, wherein the selected region may be moved within the magnetoresistive sensor by successively activating a different set of said plurality of control wires.

9. The data storage system of claim 4, wherein said control circuit includes a field effect transistor for controlling the current in at least a subset of said control wires.

10. The data storage system of claim 3, wherein said control wires comprise a conductive film having a plurality of discrete conductive nanowires.

11. The data storage system of claim 1, wherein said magnetosensitive sensor is a magnetoresistive sensor and said means for detecting includes a circuit for detecting a change in the electrical resistance of said magnetoresistive sensor.

36. The data storage system of claim 9 wherein said subset of control wires are activated in a sweeping manner to form a word line, by electrically coupling said field effect transistor device to said subset of control wires.

37. The data storage system of claim 36 wherein said field effect transistor is coupled to the word line conductors at a sweep zone on the field effect transistor by connecting the lateral face of the field effect transistor channel to the word line conductors.

38. The data storage system of claim 37 wherein the channel of said field effect transistor is oriented at an angle to widen the sweep zone over which the conductors may be connected.

39. The data storage system of claim 37 wherein the doping concentration within the channel of said field effect transistor is gradually varied across the channel width to widen the sweep zone over which the conductors may be connected.

40. The data storage system of claim 37 wherein a voltage is applied across gate electrode of said field effect transistor to cause the depletion zone within the field effect transistor channel to be gradually varied across the channel width and to widen the sweep zone over which the conductors may be connected.

12. A method of reading data stored on a data storage medium, comprising the steps of:

(A) locating a magnetosensitive sensor proximate to a magnetic storage medium having stored data in the form of a spatially distributed magnetic field;

(B) generating a spatially distributed control field within the magnetosensitive sensor to change the sensitivity of a region of the magnetosensitive sensor to the magnetic field on said magnetic storage medium; and

,

(C) detecting a change in the properties of said magnetosensitive sensor to read the data stored on a corresponding region of the magnetic storage medium, in response to changing the sensitivity of the region to the magnetic field on the magnetic storage medium.

13. The method of claim 12, wherein said step of locating includes fixing portions of said magnetoresistive sensor and said magnetic storage medium with respect to one another.

14. The method of claim 12, wherein said magnetosensitive sensor includes a magnetosensitive film, and further includes a plurality of electrically conductive control wires, spatially distributed within a plane parallel to or coincident with said magnetosensitive film, whereupon a passing of an electric current through a set of said control wires generates a magnetic field in the vicinity of said set of control wires and changes the magnetic sensitivity of a corresponding region of said magnetosensitive film.

15. The method of claim 14, wherein said step of generating includes selecting a set of said control wires through which to pass electric current.

16. The method of claim 12, further comprising moving the selected region of changed sensitivity within the magnetoresistive sensor by successively selecting different sets of control wires through which to pass electric current.

17. The method of claim 12, wherein said selected region corresponds to a single data storage location of the storage medium.

18. The method of claim 14, wherein said magnetosensitive sensor includes a two-dimensional matrix of substantially orthogonal control wires, and wherein said step of generating a control field to sensitize a portion of magnetosensitive film includes passing a current through a set of two or more control wires, including at least one wire in each direction of said matrix.

19. The method of claim 18, wherein the selected region may be moved within the magnetoresistive sensor by successively activating a different set of said plurality of control wires.

20. The method of claim 15, wherein said wherein said control wires are selected by coupling a field effect transistor to said control wires to control the current therein.

21. The method of claim 14, wherein said control wires comprise a conductive film having a plurality of discrete conductive nanowires.

22. The method of claim 12, wherein said magnetosensitive sensor is a magnetoresistive sensor and said means for detecting includes a circuit for detecting a change in the electrical resistance of said magnetoresistive sensor.

23. A data storage system for the storage and retrieval of data information, comprising:

a magnetic storage medium for storing data in a plurality of data storage regions;

a magnetoresistive sensor, proximate to, and fixed in position with respect to, said magnetic storage medium, said magnetoresistive sensor including

a magnetoresistive film having an electrical resistance which varies upon application of an external magnetic field, and,

a plurality of electrically conductive control wires, spatially distributed within a plane parallel to or coincident with the plane of said magnetoresistive film;

a control circuit for passing electric current through a selected set of said control wires, to vary the sensitivity of a selected region of said magnetoresistive film corresponding to a data storage region of said magnetic storage medium; and

,

a readout circuit for determining the resistance of said magnetoresistive film corresponding to data stored on said data storage medium in a region corresponding to said selected region.

24. The data storage system of claim 23, wherein the selected region of changed sensitivity may be moved within the magnetoresistive sensor by successively selecting different sets of control wires through which to pass electric current.

25. The data storage system of claim 23, wherein said selected region corresponds to a single data storage location of the storage medium.

26. The data storage system of claim 23, wherein said plurality of control wires forms a two-dimensional matrix of substantially orthogonal wires, wherein the portion of magnetoresistive film to be desensitized is selected by passing a current through a set of two or more control wires, including at least one wire in each direction of said matrix.

27. The data storage system of claim 23, wherein the selected region may be moved within the magnetoresistive sensor by successively activating a different set of said plurality of control wires.

28. The data storage system of claim 23, wherein said control circuit includes a field effect transistor for controlling the current in said control wires.

29. The data storage system of claim 23, wherein said control wires comprise a conductive film having a plurality of discrete conductive nanowires.

41. The data storage system of claim 28 wherein said subset of control wires are activated in a sweeping manner to form a word line, by electrically coupling said field effect transistor device to said subset of control wires.

42. The data storage system of claim 41 wherein said field effect transistor is coupled to the word line conductors at a sweep zone on the field effect transistor by connecting the lateral face of the field effect transistor channel to the word line conductors.

43. The data storage system of claim 42 wherein the channel of said field effect transistor is oriented at an angle to widen the sweep zone over which the conductors may be connected.

44. The data storage system of claim 42 wherein the doping concentration within the channel of said field effect transistor is gradually varied across the channel width to widen the sweep zone over which the conductors may be connected.

45. The data storage system of claim 42 wherein a voltage is applied across the gate electrode of said field effect transistor to cause the depletion zone within the field effect transistor channel to be gradually varied across the channel width and to widen the sweep zone over which the conductors may be connected.

30. A method of reading data stored on a data storage medium, comprising the steps of:

(A) locating a magnetoresistive sensor proximate to, and fixed in space with respect to, a magnetic storage medium having stored data in the form of a spatially distributed magnetic field, the magnetoresistive sensor including a magnetoresistive film, and a plurality of electrically conductive control wires, spatially distributed within a plane parallel to or coincident with the plane of said magnetoresistive film;

(B) passing electric current through a selected set of control wires to generate a spatially distributed control field within said magnetoresistive sensor to change the sensitivity of a region of said magnetoresistive sensor to the magnetic field on said magnetic storage medium; and

,

(C) detecting a change in the properties of said magnetoresistive sensor and hence the data stored on a corresponding region of the magnetic storage medium, in response to changing the sensitivity of said region to the magnetic field on said magnetic storage medium.

31. The method of claim 30 further comprising moving the selected region of changed sensitivity within the magnetoresistive sensor by successively selecting different sets of control wires through which to pass electric current.

32. The method of claim 30 wherein said selected region corresponds to a single data storage location of the storage medium.

33. The method of claim 30 wherein said magnetoresistive sensor includes a two-dimensional matrix of substantially orthogonal control wires, and wherein said step of generating a control field to sensitize a portion of magnetoresistive film includes passing a current through a set of two or more control wires, including at least one wire in each direction of said matrix.

34. The method of claim 30 wherein said step of detecting includes using a field effect transistor to control the current in at least a subset of said control wires.

35. The method of claim 30 wherein said control wires comprise a conductive film having a plurality of discrete conductive nanowires.