Nanostructured magnetoresistive network and corresponding method for detection of magnetic field

• US 7,352,178 B2
• Filed: 08/14/2006
• Issued: 04/01/2008
• Est. Priority Date: 10/26/2005
• Status: Expired due to Fees

• Current Assignee: C.R.F. Societa Consortile Per Azioni
• Original Assignee: Cefla Societa' Cooperativa
• Inventors: Pullini, Daniele, Ruotolo, Antonio
• Primary Examiner(s): LEDYNH, BOT L
• Application Number:
  US11/503,265
• Publication Number:
  US 20070090835A1
• Time in Patent Office: 596 Days
• Field of Search: 324/244, 324/249, 324/252, 324/260, 324/207.21, 977700-701, 977/810, 977/838, 977/953, 977/960
• US Class Current: 324/252
• CPC Class Codes: G01R 33/09 Magnetoresistive devices
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: Y10S 977/953 Detector using nanostructure

Abstract

Described herein is a magnetoresistive network responsive to a magnetic field of the type comprising a plurality of magnetoresistive elements. According to the invention, the one or more magnetoresistive elements comprise at least one magnetoresistive element in the form of nanoconstriction, the nanoconstriction comprising at least two pads made of magnetic material, associated to which are respective magnetizations oriented in directions substantially opposite to one another and connected through a nanochannel, the nanochannel being able to set up a domain wall that determines an electrical resistance of the nanoconstriction as a function of the position, with respect to said nanochannel, of said domain wall formed in said sensor device.

Claims

1. A magnetoresistive network responsive to a magnetic field of the type comprising a plurality of magnetoresistive elements, wherein one or more said plurality of magnetoresistive elements comprise at least one magnetoresistive element in the form of nanoconstriction, said nanoconstriction comprising at least two pads made of magnetic material, associated to which are respective magnetizations oriented in directions substantially opposite to one another and connected through a nanochannel, said nanochannel being able to set up a domain wall that determines an electrical resistance of said nanoconstriction as a function of the position, with respect to said nanochannel, of said domain wall formed in a sensor device.

2. The magnetoresistive network according to claim 1, wherein said nanochannel has a variable cross section along an axis of the nanochannel.

3. The magnetoresistive network according to claim 2, wherein said variable cross section assumes maximum values at the ends of the nanochannel and a minimum value in a substantially mid point of said nanochannel.

4. The magnetoresistive network according to claim 1, wherein said nanoconstriction comprises current lines, which carry pinning currents, comprising at least one component perpendicular to the axis of the nanochannel, said pinning currents being designed to change for each device the value of the respective switching field.

5. The magnetoresistive network according to claim 2, wherein said pads are obtained via permanent magnetic materials.

6. The magnetoresistive network according to claim 1, wherein said at least two pads comprise a first ferromagnetic pad and a second ferromagnetic pad that are configured geometrically for further controlling parameters of the hysteresis cycle, said parameters of the hysteresis cycle including the slope and/or the curvature and/or the coercitive field and/or the saturation field and/or the remanence field.

7. The magnetoresistive network according to claim 6, wherein said first ferromagnetic pad and/or said second ferromagnetic pad are configured with values of size and/or of distance between them calculated as a function of a desired mobility of the moments of magnetic dipole present in the nanochannel.

8. The magnetoresistive network according to claim 3, wherein it is configured for forcing in said pinning lines currents designed to magnetize the pads of the nanoconstriction in an antiferromagnetic configuration so as to bring about nucleation of the domain wall.

9. The magnetoresistive network according to claim 3, wherein it is configured for modulating the pinning currents during operation for compensating for variations in temperature and/or variations of airgap.

10. The magnetoresistive network according to claim 3, wherein it is configured for modulating the pinning currents for controlling the dynamic range of said sensor device and/or the switching fields and/or the slope of its magnetization curve.

11. The magnetoresistive network according to claim 1, wherein it is of the current-in-plane type and the nanochannel is planar.

12. The magnetoresistive network according to claim 1, wherein said sensor device is of the current-perpendicular-to-plane type and the nanochannel is vertical and obtained in a porous matrix.

13. The magnetoresistive network according to claim 1, wherein said magnetoresistive elements are at least in part arranged in series and have a respective switching field.

14. The magnetoresistive network according to claim 13, wherein said magnetoresistive elements set in series receive a constant sensing current and produce at output a series voltage value due to the sum of the voltage drops on each of said magnetoresistive elements.

15. The magnetoresistive network according to claim 13, wherein said magnetoresistive elements are at least in part set in parallel and have a respective switching field.

16. The magnetoresistive network according to claim 13, wherein said magnetoresistive elements set in parallel receive a constant voltage and produce at output a value of parallel current due to the sum of parallel currents that traverse each of said magnetoresistive elements.

17. The magnetoresistive network according to claim 13, wherein it is comprised in a magnetometric apparatus.

18. The magnetoresistive network according to claim 1, wherein it is configured according to a calculation logic scheme that can be controlled by an external magnetic field.

19. The magnetoresistive network according to claim 18, wherein said calculation logic envisages use of the pinning lines to apply said magnetic field to which said network is responsive.

20. The magnetoresistive network according to claim 1, wherein it is configured for providing memory elements controllable by means of an external magnetic field, said external field being produced by the pinning lines.

21. The magnetoresistive network according to claim 20, wherein said memory elements comprise a nanochannel modulated with a plurality of restrictions.

22. The magnetoresistive network according to claim 20, wherein said pinning lines determine a specific magnetic field for each magnetoresistive element.

23. The magnetoresistive network according to claim 10, wherein it is configured for modulating the pinning currents for controlling the dynamic range of said sensor device and/or the switching fields and/or the slope of its magnetization curve by varying values of said pinning currents in time.

24. A method for detecting magnetic fields that envisages detecting a magnetic field by measuring a magnetic control field, wherein it envisages use of a magnetoresistive network according to claim 1.