Magnetic spin polarisation and magnetisation rotation device with memory and writing process, using such a device

• US 20020105823A1
• Filed: 11/23/2001
• Published: 08/08/2002
• Est. Priority Date: 12/07/2000
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: Rodmacq, Bernard, Dieny, Bernard, Redon, Olivier
• Granted Patent: US 6,532,164 B2
• Time in Patent Office: Days
• US Class Current: 365/97
• 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: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1659 Cell access
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/3268 the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn
• CPC Class Codes: H01F 10/3286 Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy
• CPC Class Codes: H10B 61/20 comprising components having three or more electrodes, e.g. transistors
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

Magnetic spin polarising and magnetisation rotation device with memory and writing process, using such a device.

According to the invention, the device includes a means of polarising the spin of electrons, which consists of a magnetic layer (20) whose magnetisation is perpendicular to the plane of magnetisation of the respective anchored (12) and free (16) layers. The magnetisation in the free layer (16) then rotates within a plane, which is either the plane of the layer, or a perpendicular plane.

Application in the manufacture of magnetic memories.

Claims

1. Magnetic device consisting of

a first magnetic layer (12, 62) called the “

anchored”

layer which has a fixed magnetisation direction,

a second magnetic layer (16, 66) called the “

free”

layer which has a variable magnetisation direction,

an insulating or semi-conducting layer (14, 64) which separates the anchored layer (12, 62) from the free layer (16, 66),

means (24, 74, 26, 76) for passing a current of electrons through and perpendicular to the layers,

means for polarising the spin of the electrons,

characterised in that the means for polarising the spin of the electrons include at least one magnetic layer (20, 70) whose magnetisation is perpendicular to the plane of the magnetisation of free layer (16, 66), this magnetic polarisation layer (20, 70) being separated from the free layer (16, 66) by a non-magnetic conducting layer (18, 64).

2. Device in accordance with claim 1, in which the magnetic polarisation layer (20) is a layer whose magnetisation is perpendicular to the plane of the layers (12, 14, 16, 20), and in which the magnetisation of the anchored (12) and free (16) layers are located within the plane of the said layers, the spin of the electrons acting on the magnetisation of the free layer (16 ) then being polarised perpendicularly to the plane of the free layer (16) and the magnetisation of the latter rotating within the plane of the said free layer (16).

3. Device in accordance with claim 2, in which the magnetisation of the anchored layer (12) is located within the plane of the layer.

4. Device in accordance with claim 2, in which the magnetic polarisation layer consists of a stack of layers (20).

5. Device in accordance with claim 4, in which the stack of layers consists of alternate layers of materials taken from the group consisting of Fe, Pt, Pd, Co, Au and their alloys.

6. Device in accordance with claim 1, in which the magnetic polarisation layer (70) is a layer whose magnetisation is parallel to the plane of the layers, and in which the magnetisation of the anchored (62) and free (66) layers is located in a plane perpendicular to the said layers, the spin of the electrodes acting on the free layer (66) then being polarised parallel to the said layer and its magnetisation rotating in a plane perpendicular to the said free layer (66).

7. Device in accordance with claim 6, in which the free layer (66) exhibits anisotropy in a plane perpendicular to the said free layer.

8. Device in accordance with claim 6, in which the anchored layer (62) is magnetised perpendicularly to the said anchored layer.

9. Device in accordance with claim 6, in which the magnetic polarisation layer (70) is made of a material taken from the group consisting of Fe, Ni, Co and their alloys.

10. Device in accordance with claim 6, in which the free layer (66) consists of several magnetic layers (661, 663, 665, 667) separated by conducting non-magnetic layers (662, 664, 666).

11. Memory consisting of a matrix of memory cells addressable in rows and columns, characterised in that each memory cell consists of a magnetic device (60) in accordance with any of claims 1 to 10, and by a current switching device (70) connected in series with the magnetic device (60), each magnetic device (60) being connected to an addressing row (80) and each switching device (70 ) to an addressing column (90).

12. Memory in accordance with claim 11, including additionally a reference column (100) and means for comparing the voltage read at the terminals of the magnetic device (60) located at the intersection between a row (80) and a column (90), and the voltage read at the terminals of the magnetic device located on the same row (80) but in the reference column (100).

13. Data writing process in a device in accordance with any of claims 1 to 10, characterised in that:

a current of electrons is passed through the device and perpendicularly to the plane of the layers, the said polarising means polarising the electrons in a direction perpendicular to the plane of the magnetisation of the free layer, the said magnetisation then rotating within that plane,

the said current is cut off when the magnetisation of the free layer is either parallel or anti-parallel to the magnetisation of the anchored layer.