BISTABLE MAGNETIC DEVICE

• US 3,820,090 A
• Filed: 04/25/1972
• Issued: 06/25/1974
• Est. Priority Date: 01/26/1970
• Status: Expired due to Term

• Current Assignee: John Richard Wiegand
• Original Assignee: John Richard Wiegand
• Inventors: Wiegand, John Richard
• Primary Examiner(s): Moffitt, James W.
• Application Number:
  US05/247,356
• Time in Patent Office: 791 Days
• Field of Search: 340/174PM,174VC,174ZB
• US Class Current: 365/133
• CPC Class Codes: G06K 7/083 inductive G06K7/10336 takes precedence
• CPC Class Codes: G11C 11/5607 using magnetic storage elements
• CPC Class Codes: H01F 1/0304 adapted for large Barkhausen jumps or domain wall rotations, e.g. WIEGAND or MATTEUCCI effect H01F1/143 and H01F1/15391 take precedence
• CPC Class Codes: H03K 3/45 by the use, as active elements, of non-linear magnetic or dielectric devices
• CPC Class Codes: Y10S 428/928 Magnetic property
• CPC Class Codes: Y10T 428/12465 having magnetic properties, or preformed fiber orientation coordinate with shape

Abstract

A bistable ferromagnetic wire of generally uniform composition having a central relatively '"'"''"'"''"'"''"'"'soft'"'"''"'"''"'"''"'"' core portion and an outer relatively '"'"''"'"''"'"''"'"'hard'"'"''"'"''"'"''"'"' magnetized shell portion with relatively low and high coercivity respectively and whereby (a) the magnetized shell portion is operable for magnetizing the core portion in a first direction, (b) the magnetization of the core portion is reversible by application of a separate magnetic field and (c) the shell portion is operable to remagnetize the core portion in the first direction upon removal of the separate magnetic field.

Claims

1. A unitary magnetic device having first and second magnetic portions, at least said first portion being capable of retaining net magnetization after being subjected to a magnetic field, the net coercivity of said first portion being substantially greater than the net coercivity of said second portion, said first portion having substantially the same chemical composition as does said second portion, said portions being separated solely by a magnetic domain interface when said first portion has a net magnetization in a first direction and said second portion has a net magnetization in a second direction substantially opposite from said first direction.

2. The device of claim 1 whrein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of said first portion being substantially parallel to the easy axis of said anisotropy of said second portion.

3. The device of claim 1 wherein said coercivity of said portions varies in a substantially continuous fashion throughout said portion and throughout said device.

4. The device of claim 3 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of said first portion being substantially parallel to the easy axis of said anisotropy of said second portion.

5. The device of claim 1 wherein each of said portions has a generally uniform chemical composition throughout.

6. The device of claim 5 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of said first portion being substantially parallel to the easy axis of said anisotropy of said second portion.

7. The device of claim 5 wherein said coercivity of said portions varies in a substantially continuous fashion throughout said portion and throughout said device.

8. The device of claim 7 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of said first portion being substantially parallel to the easy axis of said anisotropy of said second portion.

9. The device of claim 1 wherein said magnetic domain interface is a domain wall.

10. The device of claim 9 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of said portion being substantially parallel to the easy axis of said anisotropy of said second portion.

11. The device of claim 9 wherein said coercivity of said portions varies in a substantially continuous fashion throughout said portion and throughout said device.

12. The device of claim 11 wherein said portions each have magnetic anisotropy energy, The easy axis of said anisotropy of said first portion being substantially parallel to the easy axis of said anisotropy of said second portion.

13. The device of claim 9 wherein each of said portions has a generally uniform chemical composition throughout.

14. The device of claim 13 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of said first portion being substantially parallel to the easy axis of said anisotropy of said second portion.

15. The device of claim 13 wherein said coercivity of said portions varies in a substantially continuous fashion throughout said portion and throughout said device.

16. The device of claim 15 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of said first portion being substantially parallel to the easy axis of said anisotropy of said second portion.

17. A unitary magnetic wire device having shell and core magnetic portions, At least said shell portion being capable of retaining net magnetization after being subjected to a magnetic field, the net coercivity of said shell portion being substantially greater than the net coercivity of said core portion, said shell portion having substantially the same chemical composition as does said core portion, said portions being separated solely by a magnetic domain interface when said shell portion has a net magnetization in a first direction and said core portion has a net magnetization in a second direction substantially opposite from said direction.

18. The wire of claim 17 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of both of said portions being substantially axial.

19. The wire of claim 17 wherein the magnitude of said coercivity of said portions varies in a substantially continuous fashion as a function of distance along the radius of said wire.

20. The wire of claim 19 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of both of said portions being substantially axial.

21. The wire of claim 17 wherein each of said portions has a generally uniform chemical composition throughout.

22. The wire of claim 21 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of both of said portions being substantially axial.

23. The wire of claim 21 wherein the magnitude of said coercivity of said portions varies in a substantially continuous fashion as a function of distance along the radius of said wire.

24. The wire of claim 23 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of both of said portions being substantially axial.

25. The wire of claim 17 wherein said magnetic domain interface is a domain wall.

26. The wire of claim 25 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of both of said portions being substantially axial.

27. The wire of claim 25 wherein the magnitude of said coercivity of said portions varies in a substantially continuous fashion as a function of distance along the radius of said wire.

28. The wire of claim 27 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of both of said portions being substantially axial.

29. The wire of claim 25 wherein each of said portions has a generally uniform chemical composition throughout.

30. The wire of claim 29 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of both of said portions being substantially axial.

31. The wire of claim 29 wherein the magnitude of said coercivity of said portions varies in a substantially continuous fashion as a function of distance along the radius of said wire.

32. The wire of claim 31 wherein said portions each have magnetic anisotropy energy, the easy axis of said anisotropy of both of said portions being substantially axial.