NON-VOLATILE MAGNETIC TUNNEL JUNCTION TRANSISTOR

• US 20120120719A1
• Filed: 11/13/2010
• Published: 05/17/2012
• Est. Priority Date: 11/13/2010
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Worledge, Daniel C.
• Granted Patent: US 8,482,968 B2
• Time in Patent Office: Days
• US Class Current: 365/158
• 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 11/1655 Bit-line or column circuits
• CPC Class Codes: G11C 11/1659 Cell access
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

An example embodiment is an apparatus for controlling a magnetic direction of a magnetic free layer. The apparatus includes a writer with a first magnetic write layer and a second magnetic write layer. Applying a write voltage across first and second magnetic write layers causes a magnetic anisotropy of one of the magnetic write layers to switch from parallel to the plane of the magnetic write layers to orthogonal to the plane of the magnetic write layers. The magnetic write layer with the magnetic anisotropy parallel to the plane of the magnetic write layers induces the magnetic direction in the magnetic free layer.

Claims

1. An apparatus for creating a magnetic field, the apparatus comprising:

a writer including a first magnetic write layer and a second magnetic write layer;

wherein the writer, when energized by a first write voltage, is configured to switch a magnetic anisotropy of the first magnetic write layer from parallel to the plane of the first magnetic write layer to orthogonal to the plane of the first magnetic write layer such that the second magnetic write layer induces a first magnetic field in a region proximate the writer; and

wherein the writer, when energized by a second write voltage, is configured to switch a magnetic anisotropy of the second magnetic write layer from parallel to the plane of the second magnetic write layer to orthogonal to the plane of the second magnetic write layer such that the first magnetic write layer induces a second magnetic field in the region proximate the writer, the second magnetic field being in a direction opposite the first magnetic field.

2. The apparatus of claim 1, wherein the polarity of first write voltage is opposite to the polarity of the second write voltage.

3. The apparatus of claim 1, wherein the writer further comprises:

a first write electrode electrically coupled to the first magnetic write layer;

a second write electrode electrically coupled to the second magnetic write layer; and

a dielectric write layer disposed between the first magnetic write layer and the second magnetic write layer.

4. The apparatus of claim 3, wherein:

a first write voltage applied across the first and second write electrodes causes the magnetic anisotropy of the first magnetic write layer to be orthogonal to the plane of the magnetic first write layer; and

a second write voltage applied across the first and second write electrodes opposite in polarity to the first write voltage causes the magnetic anisotropy of the second magnetic write layer to be orthogonal to the plane of the second magnetic write layer.

5. The apparatus of claim 1, wherein the first and second magnetic write layers are substantially iron (Fe).

6. The apparatus of claim 5, wherein the dielectric write layer is substantially magnesium oxide (MgO).

7. The apparatus of claim 1, wherein the region proximate to the writer includes a magnetic free layer of a magnetic tunnel junction (MTJ), the resistance of the magnetic tunnel junction is dependent on the magnetic direction of the magnetic free layer.

8. The apparatus of claim 7, further comprising a dielectric isolation layer electrically isolating the writer from the magnetic tunnel junction.

9. The apparatus of claim 8, wherein the magnetic tunnel junction comprises:

a magnetic reference layer having a magnetic direction pinned to a preset magnetic direction along the plane of the magnetic reference layer; and

a dielectric tunnel barrier configured to allow electrons to tunnel between the magnetic reference layer and the magnetic free layer.

10. The apparatus of claim 9, wherein the magnetic tunnel junction comprises:

a first MTJ electrode disposed between the dielectric isolation layer and the magnetic free layer, the first MTJ electrode being electrically coupled to the magnetic free layer; and

a second MTJ electrode electrically coupled to the magnetic reference layer.

11. A method for creating a magnetic field, the method comprising:

applying a write voltage across first and second magnetic write layers such that a magnetic anisotropy of one of the first and second magnetic write layers switches from parallel to the plane of the magnetic write layers to orthogonal to the plane of the magnetic write layers such that the magnetic write layer with the magnetic anisotropy parallel to the plane of the magnetic write layers induces the magnetic field.

12. The method of claim 11, wherein the magnetic direction of the first magnetic write layer when parallel to the plane of the magnetic write layers is opposite to the magnetic direction of the second magnetic write layer when parallel to the plane of the magnetic write layers.

13. The method of claim 11, wherein applying the write voltage across the first and second magnetic write layers comprises:

applying a first voltage potential to a first write electrode, the first write electrode being electrically coupled to the first magnetic write layer; and

applying a second voltage potential to a second write electrode, the second write electrode being electrically coupled to the second magnetic write layer.

14. The method of claim 13, wherein:

a first write voltage applied across the first and second write electrodes causes the magnetic anisotropy of the first magnetic write layer to be orthogonal to the plane of the magnetic first write layer; and

a second write voltage applied across the first and second write electrodes opposite in polarity to the first write voltage causes the magnetic anisotropy of the second magnetic write layer to be orthogonal to the plane of the second magnetic write layer.

15. The method of claim 11, wherein the first and second magnetic write layers are substantially iron (Fe).

16. The method of claim 11, further comprising:

adjusting a resistance of a magnetic tunnel junction (MTJ) disposed proximate one of the first and second magnetic write layers, wherein the resistance of the magnetic tunnel junction is dependent on the magnetic direction of a magnetic free layer receiving the induced magnetic field.

17. The method of claim 16, wherein the magnetic tunnel junction comprises:

a magnetic reference layer having a magnetic direction pinned to preset direction; and

a dielectric tunnel barrier configured to allow electrons to tunnel between the magnetic reference layer and the magnetic free layer.

18. The method of claim 17, further comprising:

applying a read current through the magnetic free layer and the magnetic reference layer.

19. A memory cell in an array of memory cells, the memory cell comprising:

a magnetic tunnel junction (MTJ) including a magnetic free layer, the resistance of the magnetic tunnel junction being dependent on the magnetic direction of the magnetic free layer; and

a writer disposed proximate the magnetic tunnel junction, the writer configured to switch a magnetic anisotropy of one of first and second magnetic write layers from parallel to the plane of the magnetic write layers to orthogonal to the plane of the magnetic write layers such that the magnetic write layer with the magnetic anisotropy parallel to the plane of the magnetic write layers induces the magnetic direction in the magnetic free layer.

20. The memory cell of claim 19, further comprising a dielectric isolation layer electrically isolating the writer from the magnetic tunnel junction.