Magnetoresistive element having three-layer buffer layer, magnetic head, magnetic reproducing apparatus, and magnetic memory

• US 7,426,098 B2
• Filed: 12/22/2004
• Issued: 09/16/2008
• Est. Priority Date: 12/25/2003
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Fukuzawa, Hideaki, Yuasa, Hiromi, Iwasaki, Hitoshi, Hashimoto, Susumu
• Primary Examiner(s): MULLIS, JEFFREY C
• Assistant Examiner(s): Kayrish; Matthew G
• Application Number:
  US11/017,965
• Publication Number:
  US 20050168887A1
• Time in Patent Office: 1,364 Days
• Field of Search: 360324-32412, 324/207.21, 324/252, 338/32.R
• US Class Current: 360/324.12
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11B 5/39 using magneto-resistive devices or effects
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: H01F 10/3259 Spin-exchange-coupled multilayers comprising at least a nanooxide layer [NOL], e.g. with a NOL spacer
• CPC Class Codes: H01F 10/3263 the exchange coupling being symmetric, e.g. for dual spin valve, e.g. NiO/Co/Cu/Co/Cu/Co/NiO
• CPC Class Codes: H01F 10/3272 by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets
• CPC Class Codes: H01F 41/325 applying a noble metal capping on a spin-exchange-coupled multilayer, e.g. spin filter deposition

Abstract

A magnetoresistive element includes a magnetoresistive film having a magnetization pinned layer whose magnetization is substantially pinned to one direction, a nonmagnetic intermediate layer, and a magnetization free layer whose magnetization is changed in direction depending on an external magnetic field, in which the magnetization pinned layer or nonmagnetic intermediate layer includes an insulator, and a pair of electrodes electrically connected to the magnetoresistive film so as to supply a sense current in a direction substantially perpendicular to a plane of the magnetoresistive film. The magnetization free layer includes a body-centered cubic layer with a body-centered cubic structure, and the thickness of the body-centered cubic layer is 2 nm or more.

Claims

1. A magnetoresistive element comprising:

a magnetoresistive film comprising;

a buffer layer;

an antiferromagnetic layer formed on the buffer layer;

a magnetization pinned layer, formed on the antiferromagnetic layer, whose magnetization is substantially pinned to one direction;

a nonmagnetic intermediate layer formed on the magnetization pinned layer; and

a magnetization free layer, formed on the nonmagnetic intermediate layer, whose magnetization is changed in direction depending on an external magnetic field; and

a pair of electrodes electrically connected to the magnetoresistive film so as to supply a sense current in a direction substantially perpendicular to a plane of the magnetoresistive film,

wherein the buffer layer comprises three layers selected from the group consisting of a Ta layer, (Ni_100-xFe_x)_100-yCr_y alloy layer (15≦

x≦

25, 20≦

y≦

30), (Ni_100-xFe_x)_100-yCr_y alloy layer (15≦

x≦

25, 30<

y≦

45), Cu layer, Ru layer, and Co_100-xFe_x layer (5<

x<

15),

and wherein the nonmagnetic intermediate layer includes at least two elements selected from the group consisting of Al, Cr, Mg, Hf, Zr, Si, Ta, Ti, V, Mo, W, Au, Ag, Cu, Pt, Nb, Re, Pd, B and C, and comprises an insulator formed of an oxide of a part of the elements and current paths penetrating the insulator and formed of another part of the elements,

and wherein the magnetization free layer comprises a body-centered cubic layer with a body-centered cubic structure, the body-centered cubic layer having a thickness of 2 nm or more.

2. The magnetoresistive element according to claim 1, wherein the magnetization free layer is formed of a (Fe_100-xCo_x)_100-yNi_y layer (0≦

x≦

85, 0≦

y≦

50) or a stacked film of a (Fe_100-xCo_x)_100-yNi_y layer (0≦

x≦

85, 0≦

y≦

50) and a Ni_100-xFe_x layer (15≦

x<

25), and wherein the (Fe_100-xCo_x)_100-yNi_y layer is in contact with the nonmagnetic intermediate layer.

3. The magnetoresistive element according to claim 1, wherein the magnetization free layer is formed of a {(Fe_100-xCo_x)_100-yNi_y}_100-zM1_z layer (0≦

x≦

85, 0≦

y≦

50, 0<

z<

10, where M1 is at least one selected from the group consisting of Cu, Au, Ag, Pt, Re and B) or a stacked film of a {(Fe_100-xCo_x)_100-yNi_y}_100-zM1_z layer (0≦

x≦

85, 0≦

y≦

50, 0<

z<

10, where M1 is at least one selected from the group consisting of Cu, Au, Ag, Pt, Re and B) and a (Ni_100-xFe_x)_100-zM2_z (15≦

x≦

25, 0<

z<

10, where M2 is at least one selected from the group consisting of Cu, Au, Ag, Pt, Re and B), and wherein the {(Fe_100-xCo_x)_100-yNi_y}_100-zM1_z layer is in contact with the nonmagnetic intermediate layer.

4. The magnetoresistive element according to claim 1, wherein the magnetization free layer is formed of ferromagnetically-coupled (Fe_100-xCo_x)_100-yNi_y layers (0≦

x≦

85, 0≦

y≦

50) and at least one Ml metal layer (where M1 is at least one selected from the group consisting of Cu, Au, Ag, Pt, Re and B) inserted between the ferromagnetically-coupled (Fe_100-xCo_x)_100-yNi_y layers, or a ferromagnetically-coupled stacked film of at least one (Fe_100-xCo_x)_100-yNi_y layer (0≦

x≦

85, 0≦

y≦

50), at least one Ni_100-xFe_x layer (15≦

x<

25) and at least one M1 metal layer (where M1 is at least one selected from the group consisting of Cu, Au, Ag, Pt, Re and B) inserted between the (Fe_100-xCo_x)_100-yNi_y layer and the Ni_100-xFe_x layer, and wherein the (Fe_100-xCo_x)_100-yNi_y layer is in contact with the nonmagnetic intermediate layer.

5. The magnetoresistive element according to claim 1, wherein the nonmagnetic intermediate layer includes at least two elements selected from the group consisting of Al, Cr, Mg, Hf, Zr, Si, Ta, Ti, V, Mo, W, Au, Ag, Cu, Pt, Nb, Re, Pd, B and C, and wherein the nonmagnetic intermediate layer comprises an insulator formed of an oxide of one of the at least two elements and current paths penetrating the insulator and formed of the other of the at least two elements.

6. The magnetoresistive element according to claim 1, wherein the buffer layer includes a Ta layer, a second layer of (Ni_100-xFe_x)_100-yCr_y alloy layer (15≦

x≦

25, 30<

y≦

45) or Ru layer, and a third layer of (Ni_100-xFe_x)_100-yCr_y alloy layer (15≦

x≦

25, 20≦

y≦

30), Cu layer or Co_100-xFe_x layer (5<

x<

15), the Ta layer being disposed distant from the antiferromagnetic layer, the third layer being disposed near the antiferromagnetic layer, and the second layer being disposed between the Ta layer and the third layer.

7. A magnetic head comprising the magnetoresistive element according to claim 1.

8. A magnetic reproducing apparatus comprising the magnetic head according to claim 7, and adapted to read information magnetically recorded in a magnetic recording medium.

9. A magnetic memory comprising a plurality of the magnetoresistive elements according to claim 1.