Non-collinear antiferromagnets for high density and low power spintronics devices
Spintronic devices based on metallic antiferromagnets having a non-collinear spin structure are provided. Also provided are methods for operating the devices. The spintronic devices are based on a bilayer structure that includes a spin torque layer of an antiferromagnetic material having a non-collinear triangular spin structure adjoining a layer of ferromagnetic material.
1. A spintronic device comprising:
a ferromagnetic layer comprising a ferromagnetic material having perpendicular magnetization;
a spin-torque layer comprising a metallic antiferromagnetic material having a non-collinear spin structure adjoining the ferromagnetic layer at an interface, the metallic antiferromagnetic material characterized in that it is capable of generating spin currents having non-zero out-of-plane spin polarizations when an in-plane charge current is passed through the spin-torque layer; and
a current source configured to pass an in-plane charge current through the spin torque layer.
2. The device of claim 1 , wherein the metallic antiferromagnetic material having a non-collinear spin structure comprises a nitride having the formula Mn 3 AN, where A is gallium, zinc, copper, or nickel.
3. The device of claim 2 , where A is gallium.
4. A method of modulating the magnetization in a spintronic device comprising:
a ferromagnetic layer comprising a ferromagnetic material having a perpendicular magnetization;
a spin-torque layer comprising a metallic antiferromagnetic material having a non-collinear spin structure in contact with the ferromagnetic layer at an interface; and
a current source configured to pass an in-plane charge current through the spin-torque layer, the method comprising:
passing an in-plane charge current through the spin-torque layer, whereby spin currents having out-of-plane spin polarizations are generated in the spin-torque layer giving rise to a spin torque in the ferromagnetic layer that modulates the magnetization of the ferromagnetic material.
5. The method of claim 4 , wherein the spin torque in the ferromagnetic layer switches the magnetization of the ferromagnetic material.
6. The method of claim 4 , wherein the metallic antiferromagnetic material having a non-collinear spin structure comprises a nitride having the formula Mn 3 AN, where A is gallium, zinc, copper, or nickel.
7. A magnetic tunnel junction device comprising;
a magnetic tunnel junction comprising:
a free magnetic layer comprising a ferromagnetic material having a perpendicular magnetization;
a pinned layer comprising a ferromagnetic material having a fixed direction of magnetization; and
a barrier layer comprising an electrically insulating material separating the ferromagnetic layer from the pinned layer;
a spin torque layer comprising a metallic antiferromagnetic material having a non-collinear spin structure in contact with the free magnetic layer at an interface, the metallic antiferromagnetic material characterized in that it is capable of generating spin currents having non-zero out-of-plane spin polarizations when an in-plane charge current is passed through the spin-torque layer;
a write current source configured to pass an in-plane charge current through the spin torque layer;
a read current source configured to pass a charge current through the magnetic tunnel junction; and
a voltage source configured to apply a bias voltage between the pinned layer and the spin-torque layer.
8. The device of claim 7 , wherein the metallic antiferromagnetic material having a non-collinear spin structure comprises a nitride having the formula Mn 3 AN, where A is gallium, zinc, copper, or nickel.
9. The device of claim 8 , where A is gallium.
10. A method of operating a magnetic tunnel junction device comprising:
a magnetic tunnel junction comprising:
a free magnetic layer comprising a ferromagnetic material having a perpendicular magnetization;
a pinned layer comprising a ferromagnetic material having a fixed direction of magnetization; and
a barrier layer comprising an electrically insulating material separating the ferromagnetic layer from the pinned layer;
a spin torque layer comprising a metallic antiferromagnetic material having a non-collinear spin structure in contact with the free magnetic layer at an interface;
a write current source configured to pass an in-plane charge current through the spin torque layer; and
a read current source configured to pass a charge current through the magnetic tunnel junction, the method comprising:
passing an in-plane write current through the spin torque layer, whereby spin currents having out-of-plane spin polarizations are generated in the spin-torque layer, giving rise to a spin torque in the free magnetic layer that switches the magnetization of the free magnetic layer; and
passing a read current through the magnetic tunnel junction and measuring the resistance of the magnetic tunnel junction.
11. The method of claim 10 , wherein the metallic antiferromagnetic material having a non-collinear spin structure comprises a nitride having the formula Mn 3 AN, where A is gallium, zinc, copper, or nickel.
12. The method of claim 11 , where A is gallium.
13. The method of claim 6 , where A is gallium.