Tuning perpendicular magnetic anisotropy of Heusler compound in MRAM devices
A device is provided. The device includes a multi-layered structure that is non-magnetic at room temperature, the multi-layered structure comprising alternating layers of Co and E, wherein E comprises at least one other element selected from the group consisting of Ge, Ga, Sn and Al, wherein a composition of the multi-layered structure is represented by Co 1−x E x , with x being in a range from 0.42 to 0.55. The device also includes a combined layer provided in contact with the multi-layered structure, the combined layer including an insertion layer comprising Co or Fe or Mn or Al in contact with a Heusler compound.
1. A device, comprising:
a multi-layered structure that is non-magnetic at room temperature, the multi-layered structure comprising alternating layers of Co and E, wherein E comprises at least one other element selected from the group consisting of Ge, Ga, Sn and Al, wherein a composition of the multi-layered structure is represented by Co 1−x E x , with x being in a range from 0.42 to 0.55; and
a combined layer in contact with the multi-layered structure, the combined layer including an insertion layer in contact with a Heusler compound, the insertion layer consisting of an element selected from the group consisting of Co, Fe, Mn and Al.
2. The device of claim 1 , wherein the combined layer is a first magnetic layer that forms part of a magnetic tunnel junction.
3. The device of claim 2 , wherein a magnetic moment of the first magnetic layer is substantially perpendicular to an interface between the multi-layered structure and the first magnetic layer.
4. The device of claim 2 , wherein the first magnetic layer has a thickness of less than 5 nm.
5. The device of claim 1 , wherein the insertion layer has a thickness of less than or equal to 3 Å.
6. The device of claim 1 , wherein the Heusler compound is a binary Heusler.
7. The device of claim 6 , wherein the Heusler compound includes one or more of Mn 3.3−x Ge, Mn 3.3−x Sn, and Mn 3.3−y Sb, with x being in a range from 0 to 0.8 for Mn 3.3−x Ge and Mn 3.3−x Sn and with y being in a range from 0 to 1.3 for Mn 3.3−y Sb.
8. The device of claim 1 , wherein Co within the multi-layered structure is replaced by a CoIr alloy and/or E includes an alloy selected from the group consisting of AlSn, AlGa, AlGe, AlGaGe, AlGaSn, AlGeSn, and AlGaGeSn.
9. The device of claim 1 , further comprising a substrate underlying the multi-layered structure.
10. The device of claim 9 , wherein a Mn x N or VN layer is interposed between the substrate and the multi-layered structure.
11. The device of claim 2 , further comprising a tunnel barrier layer overlying the first magnetic layer, thereby permitting current to pass through both the tunnel barrier layer and the first magnetic layer.
12. The device of claim 11 , comprising a second magnetic layer provided in contact with the tunnel barrier layer.
13. The device of claim 11 , wherein the tunnel barrier layer comprises MgO.
14. The device of claim 11 , wherein the tunnel barrier layer comprises Mg 1−z Al 2+(2/3)z O 4 , wherein −0.5<z<0.5.
15. A method, comprising:
using a device as a memory element, the device including:
a multi-layered structure that is non-magnetic at room temperature, the multi-layered structure comprising alternating layers of Co and E, wherein E comprises at least one other element selected from the group consisting of Ge, Ga, Sn and Al, wherein a composition of the multi-layered structure is represented by Co 1−x Ex, with x being in a range from 0.45 to 0.55; and
a combined layer in contact with the multi-layered structure, the combined layer including an insertion layer in contact with a Heusler compound, the insertion layer consisting of an element selected from the group consisting of Co, Fe, Mn and Al.
16. The method of claim 15 , wherein the memory element is a racetrack memory device.
17. A magnetic tunnel junction device, comprising:
a substrate;
a multi-layered structure that is non-magnetic at room temperature, the multi-layered structure comprising alternating layers of Co and E, wherein E comprises at least one other element selected from the group consisting of Ge, Ga, Sn and Al, wherein a composition of the multi-layered structure is represented by Co 1−x E x , with x being in a range from 0.42 to 0.55; and
a first magnetic layer in contact with the multi-layered structure, the first magnetic layer including an insertion layer in contact with a Heusler compound, consisting of an element selected from the group consisting of Co, Fe, Mn and Al;
a tunnel barrier layer on the first magnetic layer; and
a second magnetic layer on the tunnel barrier layer.
18. The magnetic tunnel junction device of claim 17 , further comprising a synthetic anti-ferromagnetic layer on the second magnetic layer.
19. The magnetic tunnel junction device of claim 18 , wherein the first magnetic layer has a magnetic moment that is switchable, and the second magnetic layer has a magnetic moment that is fixed.
20. The magnetic tunnel junction device of claim 18 , wherein the first magnetic layer has a magnetic moment that is fixed, and the second magnetic layer has a magnetic moment that is switchable.
21. The magnetic tunnel junction device of claim 17 , wherein the Heusler compound includes one or more of Mn 3.3−x Ge, Mn 3.3−x Sn, and Mn 3.3−y Sb, with x being in a range from 0 to 0.8 for Mn 3.3−x Ge and Mn 3.3−x Sn and with y being in a range from 0 to 1.3 for Mn 3.3−y Sb.