Systems and methods for implementing magnetoelectric junctions

1. A DIOMEJ cell apparatus comprising:

a non-linear resistor; and

a magnetoelectric junction, comprising:

a ferromagnetic fixed layer magnetically polarized in a first direction;

a ferromagnetic free layer with an easy magnetic axis that is substantially aligned with the first direction, such that the ferromagnetic free layer can adopt a magnetic polarity that is either parallel with or anti-parallel with the first direction; and

a non-magnetic layer interposed between said ferromagnetic fixed layer and ferromagnetic free layer;

wherein the coercivity of the ferromagnetic, magnetically anisotropic, free layer is reduced when a potential difference is applied across the magnetoelectric junction; and

wherein the non-linear resistor and the magnetoelectric junction are arranged in series.

2. The apparatus as recited in claim 1 , wherein said non-linear resistor is a diode selected from the group consisting of a Schottky diode, a Zener diode, an avalanche diode, and a tunnel diode.

3. The apparatus as recited in claim 1 , wherein the ferromagnetic fixed layer is one or more layers of a material selected from the group of materials consisting of: iron, nickel, manganese, cobalt, palladium, platinum, boron, rhodium, FeCoB, FeGaB, FePd, FePt, CoPt, CoPd, and FeRh.

4. The apparatus as recited in claim 1 , wherein the ferromagnetic free layer is one or more layers of material selected from the group of materials consisting of: iron, nickel, manganese, cobalt, palladium, platinum, boron, rhodium, FeCoB, FeGaB, FePd, FePt, CoPt, CoPd, and FeRh.

5. The apparatus as recited in claim 1 , wherein the non-magnetic layer comprises at least one layer of a dielectric material.

6. The apparatus as recited in claim 1 , wherein each dielectric layer is a material selected from the group of materials consisting of: MgO, Al 2 O 3 , HfO x , and TaO x .

7. The apparatus as recited in claim 1 , further comprising a seed layer of a material with large spin-orbit coupling attached to the ferromagnetic free layer.

8. The apparatus as recited in claim 7 , wherein the seed layer comprises a material selected from the group of materials consisting of: Tantalum, Hafnium, Molybdenum, Tungsten, Iridium, Magnesium, Chromium, and Ruthenium.

9. The apparatus as recited in claim 7 , wherein the seed layer comprises two or more layers of a material selected from the group of materials consisting of: Tantalum, Hafnium, Molybdenum, Tungsten, Iridium, Magnesium, Chromium, and Ruthenium.

10. The apparatus as recited in claim 7 , wherein the seed layer comprises one or more topological insulating materials selected from the group of materials consisting of: Bi, Se, Sb, and Te.

11. The apparatus as recited in claim 1 , further comprising a second ferromagnetic fixed layer with its magnetization substantially perpendicular to that of the first ferromagnetic fixed layer and ferromagnetic free layer.

12. The apparatus as recited in claim 11 , wherein said second ferromagnetic fixed layer comprises a high-moment magnetic material.

13. The apparatus as recited in claim 12 , wherein said high-moment magnetic material comprises at least one element selected from the group of elements consisting of: Fe, N, Zr, Hf, Ta, Ti, Co, Pt, Pd and B.

14. The apparatus as recited in claim 11 , wherein said second ferromagnetic fixed layer comprises a hard magnetic material.

15. The apparatus as recited in claim 14 , where said hard magnetic material comprises at least one element selected from the group of elements consisting of: Fe, Nd, Co, and B.

16. The apparatus as recited in claim 11 , wherein said second ferromagnetic fixed layer comprises an exchange-biased magnetic material.

17. The apparatus as recited in claim 16 , where said exchange-biased magnetic material comprises at least one element selected from the group of elements consisting of: Fe, Co, and B disposed in close proximity to an anti-ferromagnetic material selected from the group of PtMn and IrMn.

18. The apparatus as recited in claim 1 , said magnetoelectric junction further comprising:

a second fixed layer; and

at least one second dielectric layer interposed between the ferromagnetic free layer and the second fixed layer;

wherein the second fixed layer has a direction of magnetic polarization that is perpendicular to the direction of magnetic polarization of the first ferromagnetic fixed layer.

19. A magneto-electric random access memory apparatus, comprising:

(a) a plurality of source lines;

(b) a plurality of bit lines; and

(c) an array of DIOMEJ cells electrically coupled to at least one source line and at least one bit line, each DIOMEJ cell comprising:

(i) a non-linear resistor;

(ii) a ferromagnetic fixed layer magnetically polarized in a first direction;

(iii) a ferromagnetic free layer with an easy magnetic axis that is substantially aligned with the first direction, such that the ferromagnetic free layer can adopt a magnetic polarity that is either parallel with or antiparallel with the first direction; and

(iv) a non-magnetic layer interposed between said ferromagnetic fixed layer and a ferromagnetic free layer;

wherein the coercivity of the ferromagnetic, magnetically anisotropic, free layer is reduced when a potential difference is applied across the magnetoelectric junction;

wherein the non-linear resistor and the magnetoelectric junction are arranged in series;

wherein each DIOMEJ cell is electrically connected to a unique combination of a source line and a bit line, such that no other DIOMEJ cell is connected to the same bit line and the same source line; and

wherein the source line and the bit line can be used to establish a potential difference across a particular DIOMEJ cell.

20. The apparatus as recited in claim 19 , wherein for at least one DIOMEJ cell in the array, the first direction coincides with an in-plane direction.

21. The apparatus as recited in claim 19 , wherein for at least one DIOMEJ cell in the array, the first direction coincides with an out-of-plane direction.

22. The apparatus as recited in claim 19 , wherein the application of a threshold potential difference across the ferromagnetic fixed layer and the ferromagnetic free layer reduces the coercivity of the ferromagnetic free layer to an extent where the strength of a magnetic field imposed by a current through an adjacent source line or bit line of an adjacent cell is sufficient to switch the direction of magnetic polarization of the ferromagnetic free layer.

23. The apparatus as recited in claim 19 , wherein for at least one DIOMEJ cell in the array, the application of a threshold potential difference across the ferromagnetic fixed layer and the ferromagnetic free layer reduces the coercivity of the ferromagnetic free layer to an extent that the strength of current-induced spin torque imposed by an electric current through a metal source line or bit line that is connected to the ferromagnetic free layer is sufficient to switch the direction of magnetic polarization of the ferromagnetic free layer.

24. The apparatus as recited in claim 19 , wherein for at least one DIOMEJ cell in the array, the coercivity of the ferromagnetic free layer is reduced when a potential difference is applied across the magnetoelectric junction.

25. The apparatus as recited in claim 19 , wherein for at least one DIOMEJ cell, the direction of magnetic polarization of the magnetoelectric junction is inverted by the application of a potential difference pulse that has a duration that coincides with half of the precessional period of the ferromagnetic free layer, or an odd multiple thereof.

26. The apparatus as recited in claim 19 , wherein said non-linear resistor is a diode selected from the group consisting of: a semiconductor p-n junction, a Schottky metal-semiconductor connection, a metal-insulator-metal nonlinear resistor, a Zener diode, an avalanche diode, and a tunnel diode.

27. The apparatus as recited in claim 19 , said magnetoelectric junction of each cell further comprising:

a semi-fixed layer; and

a second dielectric layer interposed between the ferromagnetic free layer and the semi-fixed layer;

wherein the semi-fixed layer has a direction of magnetic polarization that is anti-parallel with the direction of magnetic polarization of the ferromagnetic fixed layer.

28. The apparatus as recited in claim 19 , said magnetoelectric junction of each cell further comprising:

a second ferromagnetic fixed layer with its magnetization substantially perpendicular to that of the first ferromagnetic fixed layer and ferromagnetic free layer.