Magnetic devices and sensors based on perovskite manganese oxide materials

• US 5,792,569 A
• Filed: 03/19/1996
• Issued: 08/11/1998
• Est. Priority Date: 03/19/1996
• Status: Expired due to Fees

• Current Assignee: Hitachi Global Storage Technologies Netherlands BV (Western Digital Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Trouilloud, Philip Louis, Lecoeur, Philippe P., Sun, Jonathan Zanhong, Gupta, Arunava, Xiao, Gang
• Primary Examiner(s): Resan, Stevan A.
• Application Number:
  US08/618,184
• Time in Patent Office: 875 Days
• Field of Search: 428/692, 428/693, 428/701, 428/702, 428/900, 324/252, 338/32 R, 360/113
• US Class Current: 428/815
• 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: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/332 using thin films G11B5/372, G11B5/3903 take precedence
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H01F 10/3213 Exchange coupling of magnetic semiconductor multilayers, e.g. MnSe/ZnSe superlattices semiconductor materials for use in semiconductor devices H01L29/12
• CPC Class Codes: H10N 50/85 Magnetic active materials
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/1171 with defined laminate structural detail

Abstract

A tri-layer thin film magnetoresistive device using doped perovskite manganate thin films as ferromagnetic elements, wherein a current is transported through the tri-layer structure, is disclosed. A large magnetoresistance change of about a factor of two is obtained in a low magnetic field, less than 150 Oe, which is close to the coercivity of the material of the elements. This device demonstrates that low-field spin-dependent transport in the manganates can be accomplished and that the magnitude of the resulting magnetoresistance is suitable for magnetoresistive field sensor applications.

Claims

1. A tri-layer thin film magnetoresistive device comprising:

a first or bottom thin film magnetic layer;

a second or intermediate layer;

a third or top thin film magnetic layer;

wherein said second or intermediate layer is one selected from the group comprising a metal and an insulator which disrupts the magnetic exchange coupling between said first and third layers while allowing the passage of electrical current thereacross and wherein at least one of said first or third layers is a doped manganese perovskite and wherein if only one of said first and third layers is a doped perovskite then the other is a ferromagnetic element or compound which exhibits spin polarization.

2. The device of claim 1 wherein said second layer is an insulating tunneling barrier.

3. The device of claim 1 wherein said second layer is the perovskite oxide SrTiO₃.

4. The device of claim 1 wherein said first and third layers are LCMO and said second layer is STO.

5. The device of claim 1 wherein said first and third layers are LSMO and said second layer is STO.

6. The device of claim 1 wherein said first magnetic layer is situate on a substrate.

7. The device of claim 6 wherein said substrate is silicon.

8. The device of claim 6 wherein said substrate is SrTiO₃.

9. A tri-layer thin film magnetoresistive device comprising:

a first contact electrode;

a first or bottom thin film magnetic layer;

a second or intermediate layer;

a third or top thin film magnetic layer; and

a second contact electrode;

wherein said second or intermediate layer is one selected from the group comprising a metal and an insulator which disrupts the magnetic exchange coupling between said first and third layers while allowing the passage of electrical current thereacross and wherein at least one of said first or third layers is a doped manganese perovskite and wherein if only one of said first and third layers is a doped perovskite then the other is a ferromagnetic element or compound which exhibits spin polarization.

10. The device of claim 9 wherein said second layer is an insulating tunneling barrier.

11. The device of claim 9 wherein said second layer is the perovskite oxide SrTiO₃.

12. The device of claim 9 wherein said first and third layers are LCMO and said second layer is STO.

13. The device of claim 9 wherein said first and third layers are LSMO and said second layer is STO.

14. The device of claim 9 further including a protective layer inbetween said third magnetic layer and said second contact electrode.

15. The device of claim 9 wherein said first magnetic layer is situate on a substrate.

16. The device of claim 9 wherein said substrate is silicon.

17. The device of claim 9 wherein said substrate is SrTiO₃.