Magnetic tunnel junctions including crystalline and amorphous tunnel barrier materials

• US 7,443,639 B2
• Filed: 04/04/2005
• Issued: 10/28/2008
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Parkin, Stuart Stephen Papworth
• Primary Examiner(s): Renner; Craig A
• Application Number:
  US11/099,184
• Publication Number:
  US 20060221510A1
• Time in Patent Office: 1,303 Days
• Field of Search: 360/324.2
• US Class Current: 360/324.2
• 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 33/06 using galvano-magnetic devices
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

Magnetic tunnel junctions are disclosed that include ferromagnetic (or ferrimagnetic) materials and a bilayer tunnel barrier structure. The bilayer includes a crystalline material, such as MgO or Mg—ZnO, and Al₂O₃, which may be amorphous. If MgO is used, then it is preferably (100) oriented. The magnetic tunnel junctions so formed enjoy high tunneling magnetoresistance, e.g., greater than 100% at room temperature.

Claims

1. A magnetic tunnel junction, comprising:

a first layer of magnetic material selected from the group of materials consisting of ferromagnetic materials and ferrimagnetic materials;

a second layer of magnetic material selected from the group of materials consisting of ferromagnetic materials and ferrimagnetic materials; and

a bilayer of respective tunnel barriers, the bilayer being sandwiched between the first and second magnetic layers, so that the first layer, the bilayer, and the second layer form a magnetic tunnel junction, wherein;

the bilayer includes i) a layer of amorphous Al₂O₃ that forms a first tunnel baffler and ii) a layer of crystalline material that forms a second tunnel barrier, the crystalline material including MgO that is (100) or (111) oriented, and

the tunnel barriers and the magnetic layers form a magnetic tunnel junction having a tunneling magnetoresistance of at least 100% at room temperature.