Magnetoresistive element and magnetic memory

Patent metadata

Field	Value
Publication number	US-9299918-B2
Application number	US-201414504140-A
Country	US
Kind code	B2
Filing date	Oct 1, 2014
Priority date	Mar 25, 2011
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

A magnetoresistive element according to an embodiment includes: a first to third ferromagnetic layers, and a first nonmagnetic layer, the first and second ferromagnetic layers each having an axis of easy magnetization in a direction perpendicular to a film plane, the third ferromagnetic layer including a plurality of ferromagnetic oscillators generating rotating magnetic fields of different oscillation frequencies from one another. Spin-polarized electrons are injected into the first ferromagnetic layer and induce precession movements in the plurality of ferromagnetic oscillators of the third ferromagnetic layer by flowing a current between the first and third ferromagnetic layers, the rotating magnetic fields are generated by the precession movements and are applied to the first ferromagnetic layer, and at least one of the rotating magnetic fields assists a magnetization switching in the first ferromagnetic layer.

First claim

What is claimed is:

1. A magnetoresistive element comprising:
a first ferromagnetic layer having an axis of easy magnetization in a direction perpendicular to a film plane, a magnetization direction of the first ferromagnetic layer being changeable;
a second ferromagnetic layer having an axis of easy magnetization in a direction perpendicular to the film plane, a magnetization direction of the second ferromagnetic layer being fixed;
a first nonmagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer; and
a third ferromagnetic layer provided on an opposite side from the first nonmagnetic layer relative to the second ferromagnetic layer, and including a plurality of ferromagnetic oscillators generating rotating magnetic fields of different oscillation frequencies from one another, each of the oscillators having a magnetization parallel to the film plane,
the rotating magnetic fields being generated by flowing a current between the first ferromagnetic layer and the third ferromagnetic layer and at least one of the rotating magnetic fields being applied at a magnetization switching in the first ferromagnetic layer.

2. The element according to claim 1 , further comprising a spin injection layer injecting spin-polarized electrons into the third ferromagnetic layer, the spin injection layer being located between the second ferromagnetic layer and the third ferromagnetic layer.

3. The element according to claim 1 , further comprising:
a spin injection layer injecting spin-polarized electrons into the third ferromagnetic layer, the spin injection layer being located on an opposite side from the second ferromagnetic layer relative to the third ferromagnetic layer; and
a second nonmagnetic layer provided between the second ferromagnetic layer and the third ferromagnetic layer.

4. The element according to claim 1 , wherein the oscillation frequencies of the rotating magnetic fields generated from the oscillators of the third ferromagnetic layer are in the range of 0.62f 0 to 1.50f 0 , where a resonant frequency of the first ferromagnetic layer is f 0 .

5. The element according to claim 1 , wherein the third ferromagnetic layer includes a nonmagnetic matrix and a plurality of ferromagnetic grains surrounded by the nonmagnetic matrix, the ferromagnetic grains being the oscillators.

6. The element according to claim 5 , wherein
the nonmagnetic matrix of the third ferromagnetic layer is an oxide containing at least one element selected from Al, Si, Ti, Mg, Ta, Zn, Fe, Co, and Ni, and
the ferromagnetic grains contain at least one element selected from Fe, Co, and Ni.

7. The element according to claim 5 , wherein
the nonmagnetic matrix of the third ferromagnetic layer is a nonmagnetic metal material, and
the ferromagnetic grains contain at least one element selected from Fe, Co, and Ni.

8. The element according to claim 1 , wherein the third ferromagnetic layer comprises a ferromagnetic film and a nonmagnetic film, the ferromagnetic film containing at least one element selected from Fe, Co, and Ni, the nonmagnetic film containing at least one element selected from Cu, Ag, Au, and Ru.

9. The element according to claim 1 , further comprising:
a fourth ferromagnetic layer provided between the second ferromagnetic layer and the third ferromagnetic layer, and having an axis of easy magnetization in a direction perpendicular to the film plane, a magnetization direction of the fourth ferromagnetic layer being antiparallel to the magnetization direction of the second ferromagnetic layer; and
a third nonmagnetic layer provided between the second ferromagnetic layer and the fourth ferromagnetic layer,
wherein M S2 represents saturation magnetization of the second ferromagnetic layer, t 2 represents film thickness of the second ferromagnetic layer, M S4 represents saturation magnetization of the fourth ferromagnetic layer, t 4 represents film thickness of the fourth ferromagnetic layer, and the relationship, M S2 ×t 2 <M S4 ×t 4 , is satisfied.

10. A magnetic random access memory comprising:
the magnetoresistance effect element according to claim 1 ;
a first wire that is electrically connected to the first ferromagnetic layer; and
a second wire that is electrically connected to the third ferromagnetic layer.

11. The memory according to claim 1 , further comprising
a selective transistor, one of a source and a drain of which being electrically connected to one of the first and third ferromagnetic layers and the other of the source and the drain being electrically connected to one of the first and second wires.

Assignees

• Toshiba Kk

Inventors

• Daibou Tadaomi
• Amano Minoru
• Saida Daisuke
• Ito Junichi
• Ohsawa Yuichi
• Kamata Chikayoshi
• Kashiwada Saori
• Yoda Hiroaki

Classifications

• H01F10/3286

  Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy · CPC title

• H01F10/329

  Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect · CPC title

• H01F10/3272

  by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets · CPC title

• H01F10/3254 Primary

  the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ] · CPC title

• H01L43/10

  Electricity · mapped topic