Magnetic memory element with multilayered seed structure
View Patent ↗The present invention is directed to a magnetic structure, which includes a magnetic fixed layer structure formed on top of a seed layer structure. The seed layer structure includes one or more layers of a first transition metal, which may be platinum, palladium, nickel, or iridium, interleaved with one or more layers of a second transition metal, which may be tantalum, titanium, vanadium, molybdenum, chromium, tungsten, zirconium, hafnium, or niobium. The magnetic fixed layer structure has a first invariable magnetization direction substantially perpendicular to a layer plane thereof and includes layers of a first magnetic material interleaved with layers of the first transition metal. The first magnetic material may be made of cobalt.
1. A magnetic structure comprising:
a seed layer structure including one or more layers of a first transition metal interleaved with one or more layers of a second transition metal; and
a magnetic fixed layer structure formed adjacent to said seed layer structure and having a first invariable magnetization direction substantially perpendicular to a layer plane of said magnetic fixed layer structure, said magnetic fixed layer structure including layers of a first magnetic material interleaved with layers of said first transition metal.
2. The magnetic structure of claim 1 , wherein said first transition metal is nickel.
3. The magnetic structure of claim 1 , wherein said first transition metal is iridium.
4. The magnetic structure of claim 1 , wherein said first transition metal is platinum.
5. The magnetic structure of claim 1 , wherein said first transition metal is palladium.
6. The magnetic structure of claim 1 , wherein said second transition metal is tantalum.
7. The magnetic structure of claim 1 , wherein said second transition metal is titanium or vanadium.
8. The magnetic structure of claim 1 , wherein said second transition metal is hafnium or zirconium.
9. The magnetic structure of claim 1 , wherein said second transition metal is molybdenum or tungsten.
10. The magnetic structure of claim 1 , wherein said first magnetic material is cobalt.
11. The magnetic structure of claim 1 , wherein said first magnetic material and said first transition metal are cobalt and nickel, respectively.
12. The magnetic structure of claim 1 , wherein said first magnetic material and said first transition metal are cobalt and iridium, respectively.
13. The magnetic structure of claim 1 , wherein said first magnetic material and said first transition metal are cobalt and platinum, respectively.
14. The magnetic structure of claim 1 , wherein said seed layer structure is non-magnetic.
15. The magnetic structure of claim 1 , wherein said magnetic fixed layer structure includes a first magnetic fixed layer and a second magnetic fixed layer with a first perpendicular enhancement layer (PEL) interposed therebetween, each of said first and second magnetic fixed layers including one or more layers of said first magnetic material interleaved with one or more layers of said first transition metal.
16. The magnetic structure of claim 15 , wherein said first PEL is made of chromium.
17. The magnetic structure of claim 1 further comprising:
an anti-ferromagnetic coupling layer formed adjacent to said magnetic fixed layer structure opposite said seed layer structure; and
a magnetic reference layer structure formed adjacent to said anti-ferromagnetic coupling layer, said magnetic reference layer structure having a second invariable magnetization direction that is substantially perpendicular to a layer plane thereof and is substantially opposite to said first invariable magnetization direction,
wherein said magnetic reference layer structure includes a first magnetic reference layer and a second magnetic reference layer with a second perpendicular enhancement layer (PEL) interposed therebetween, said second magnetic reference layer formed adjacent to said anti-ferromagnetic coupling layer opposite said magnetic fixed layer structure and including one or more layers of a second magnetic material interleaved with one or more layers of a third transition metal.
18. The magnetic structure of claim 17 , wherein said second magnetic material and said third transition metal are cobalt and platinum, respectively.
19. The magnetic structure of claim 17 , wherein said anti-ferromagnetic coupling layer is made of iridium.
20. The magnetic structure of claim 17 further comprising:
an insulating tunnel junction layer formed adjacent to said first magnetic reference layer; and
a magnetic free layer structure formed adjacent to said insulating tunnel junction layer and including one or more magnetic free layers that have a variable magnetization direction substantially perpendicular to layer planes thereof.
21. The magnetic structure of claim 20 , wherein said magnetic free layer structure includes a first magnetic free layer and a second magnetic free layer with a third perpendicular enhancement layer (PEL) interposed therebetween.