Shiftable magnetic shift register and method of using the same

• US 6,834,005 B1
• Filed: 06/10/2003
• Issued: 12/21/2004
• Est. Priority Date: 06/10/2003
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Parkin, Stuart S. P.
• Primary Examiner(s): NGUYEN, TAN
• Application Number:
  US10/458,554
• Publication Number:
  US 20040252539A1
• Time in Patent Office: 560 Days
• Field of Search: 365/80, 365/83, 365/85, 365/55, 365/66, 365/171, 365/173
• US Class Current: 365/80
• CPC Class Codes: G11C 11/14 using thin-film elements
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: G11C 19/02 using magnetic elements G11C19/14 takes precedence
• CPC Class Codes: G11C 19/0808 using magnetic domain propagation
• CPC Class Codes: G11C 19/0841 using electric current
• CPC Class Codes: H01F 10/14 containing iron or nickel H01F10/126 , H01F10/13, H01F10/16 take precedence
• CPC Class Codes: H01F 41/26 using electric currents , e.g. electroplating

Abstract

A magnetic shift register uses the inherent, natural properties of domain walls in magnetic materials to store data. The shift register uses spin electronics without changing the physical nature of its constituent materials. The shift register comprises a fine track or strip of magnetic materials. Information is stored as domain walls in the track. An electric current is applied to the track to move the magnetic moments along the track past a reading or writing device. In a magnetic material with domain walls, a current passed across the domain wall moves the domain wall in the direction of the current flow. As the current passes through a domain, it becomes “spin polarized”. When this spin polarized current passes through the next domain and across a domain wall, it develops a circle of spin torque. This spin torque moves the domain wall.

Claims

1. A shift register, comprising:

a track made of magnetic material and comprised of;

a storage region that contains a plurality of magnetic domains for storing data; and

a reservoir region that is contiguous to the storage region;

wherein an electric current is applied to the track to shift at least some of the magnetic domains of the storage region, along the track, in a direction of the electric current, in and out of the reservoir region, in order to shift at least some of the stored data from the storage region to the reservoir region.

2. The shift register of claim 1, wherein the reservoir region is devoid of magnetic domains in a quiescent state.

3. The shift register of claim 1, wherein a reading element is disposed in proximity to the track for selectively reading data stored in the storage region when the stored data is shifted from the storage region to the reservoir region, past the reading element.

4. The shift register of claim 1, wherein a writing element is disposed in proximity to the track for selectively writing data in at least some of the magnetic domains of the storage region when the stored data is shifted from the storage region to the reservoir region, past the writing element.

5. The shift register of claim 4, wherein a reading element is disposed in proximity to the track for selectively reading the written data by when the stored data is shifted from the storage region to the reservoir region, past the reading element.

6. The shift register of claim 1, wherein the track has a generally uniform cross-sectional area along the storage region and the reservoir region.

7. The shift register of claim 1, wherein the track has a non-uniform cross-sectional area along the storage region and the reservoir region.

8. The shift register of claim 1, wherein the track comprises means for pinning at least some of the magnetic domains.

9. The shift register of claim 8, wherein the pinning means defines generally identical magnetic domains.

10. The shift register of claim 8, wherein the pinning means comprises indentations.

11. The shift register of claim 1, wherein the track is segmented into a plurality of layers of magnetic materials.

12. The shift register of claim 1, wherein the track is segmented into a plurality of data storage and reservoir regions that dynamically receive the magnetic domains.

13. The shift register of claim 1, wherein a data storage region is made of a uniform magnetic material.

14. The shift register of claim 1, wherein a data storage region is made of at least two different magnetic materials.

15. The shift register of claim 1, wherein a data storage region is comprised of adjacent domains of two different magnetic materials.

16. The shift register of claim 1, wherein the magnetic material comprises a ferromagnetic material.

17. The shift register of claim 1, wherein the magnetic material comprises a ferrimagnetic material.

18. The shift register of claim 1, wherein the track comprises a plurality of tracks.

19. The shift register of claim 18, wherein at least some of the plurality of tracks are connected in a continuous pattern.

20. The shift register of claim 18, further comprising at least one data reading element and one data writing element for each track.

21. The shift register of claim 1, further comprising a writing element for writing data in the magnetic domains.

22. The shift register of claim 1, further comprising at least one data reading element and one data writing element.

23. The shift register of claim 1, further comprising a reading element for selectively accessing the stored data.

24. The shift register of claim 1, wherein the reading element comprises a magnetic tunneling junction.

25. The shift register of claim 1, wherein the track is generally U-shaped.

26. The shift register of claim 1, wherein the track has a generally serpentine shape.

27. The shift register of claim 1, wherein the track has a generally arcuate shape.

28. The shift register of claim 1, further comprising a control circuit that is substantially disposed in a reference plane, to access the data stored in the track;

and

wherein the track is disposed out of the reference plane relative to the control circuit, to enable three-dimensional storage of data.

29. The shift register of claim 28, wherein the track is disposed at an angle relative to the reference plane.

30. The shift register of claim 29, wherein the track is disposed at an approximately 90-degree angle relative to the reference plane.

31. The shift register of claim 29, wherein the control circuit comprises at least one data reading element and one data writing element.

32. The shift register of claim 28, wherein the reference plane is defined by a plane of a semiconductor substrate on which the control circuit is formed.

33. The shift register of claim 32, wherein the reference plane lies in a horizontal plane.

34. The shift register of claim 33, wherein the track generally lies in a vertical plane.

35. The shift register of claim 34, further comprising an energy source for passing the electric current through the track to shift the magnetic domains.

36. The shift register of claim 28, wherein the track is formed on one side of the reference plane.

37. The shift register of claim 28, wherein the track comprises at least a first track and a second track;

wherein the first track is disposed on a first side of the reference plane; and

wherein the second track is disposed on a second side of the reference plane.

38. The shift register of claim 28, wherein the control circuit comprises at least one reading element for selectively accessing the stored data.

39. The shift register of claim 28, wherein the control circuit comprises a writing element for writing data in the magnetic domains.

40. The shift register of claim 28, wherein the track comprises a plurality of tracks.

41. A shift register, comprising

a magnetic storage means for storing data comprised of:

a storage region that contains a plurality of magnetic domains for storing the data; and

a reservoir region that is contiguous to the storage region; and

means for selectively shifting at least some of the magnetic domains of the storage region in and out of the reservoir region, along the track, in a direction of an electric current that is applied to the track.

42. The shift register of claim 41, wherein the reservoir region is devoid of magnetic domains in a quiescent state.

43. The shift register of claim 41, further comprising means for selectively reading data stored in the storage region when the stored data is shifted from the storage region to the reservoir region, past the reading means.

44. The shift register of claim 41, further comprising means for selectively writing data in at least some of the magnetic domains of the storage region when the stored data is shifted from the storage region to the reservoir region, past the writing means.

45. The shift register of claim 44, further comprising means for selectively reading the written data.

46. The shift register of claim 41, wherein the magnetic storage means has a generally uniform cross-sectional area along the storage region and the reservoir region.

47. The shift register of claim 41, wherein the magnetic storage means has a non-uniform cross-sectional area along the storage region and the reservoir region.

48. The shift register of claim 41, wherein the magnetic storage means comprises means for pinning at least some of the magnetic domains.

49. The shift register of claim 48, wherein the pinning means defines generally identical magnetic domains.

50. The shift register of claim 48, wherein the pinning means comprises indentations.

51. The shift register of claim 41, further comprising means for accessing the stored data;

wherein the means for accessing the stored data is substantially disposed in a reference plane; and

wherein the magnetic data storage means is disposed out of the reference plane relative to the control circuit.

52. The shift register of claim 51, wherein the magnetic data storage means is disposed at an angle relative to the reference plane.

53. The shift register of claim 52, wherein the magnetic data storage means is disposed at an approximately 90-degree angle relative to the reference plane.

54. The shift register of claim 51, wherein the reference plane is defined by a plane of a semiconductor substrate on which the control circuit is formed.

55. The shift register of claim 54, wherein the reference plane lies in a horizontal plane.

56. The shift register of claim 55, wherein the magnetic data storage means generally lies in a vertical plane.

57. The shift register of claim 56, further comprising an energy means for passing the electric current through the magnetic data storage means, to shift the magnetic domains.

58. The shift register of claim 51, wherein the magnetic data storage means is formed on one side of the reference plane.

59. The shift register of claim 51, wherein the magnetic data storage means comprises at least a first track and a second track;

wherein the first track is disposed on a first side of the reference plane; and

wherein the second track is disposed on a second side of the reference plane.

60. The shift register of claim 51, wherein the means for accessing the stored data comprises at least one reading element for selectively accessing the stored data.

61. A method of shifting data in a register, comprising:

the register is made of magnetic material, and comprises;

a storage region that contains a plurality of magnetic domains for storing the data; and

a reservoir region that is contiguous to the storage region; and

selectively shifting at least some of the magnetic domains of the storage region in and out of the reservoir region, along the track, in a direction of an electric current that is applied to the track.

62. The method of claim 61, wherein the reservoir region is devoid of magnetic domains in a quiescent state.

63. The method of claim 61, further comprising selectively reading data stored in the storage region, when the stored data is shifted from the storage region to the reservoir region, past a reading element.

64. The method of claim 61, further comprising selectively writing data in at least some of the magnetic domains of the storage region, when the stored data is shifted from the storage region to the reservoir region, past a writing element.

65. The method of claim 64, further comprising selectively reading the written data.

66. The method of claim 61, further comprising:

forming a control circuit in a reference plane; and

disposing the register out of the reference plane relative to the control circuit.

67. The method of claim 66, wherein disposing the register comprises disposing the register at an angle relative to the reference plane.

68. The method of claim 67, wherein disposing the register comprises disposing the register at an approximately 90-degree angle relative to the reference plane.

69. The method of claim 66, wherein forming the control circuit comprising defining the reference plane by a plane of a semiconductor substrate.

70. The method of claim 69, wherein the reference plane lies in a horizontal plane.