Magnetoresistance effect element and Heusler alloy
A magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer positioned between the first ferromagnetic layer and the second ferromagnetic layer, and at least one of the first ferromagnetic layer and the second ferromagnetic layer is a Heusler alloy represented by the following General Formula (1): Co 2 Fe α X β (1) (in Formula (1), X represents one or more elements selected from the group consisting of Mn, Cr, Si, Al, Ga and Ge, and α and β represent numbers that satisfy 2.3≤α+β, α<β, and 0.5<α<1.9).
1. A magnetoresistance effect element including a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer positioned between the first ferromagnetic layer and the second ferromagnetic layer,
wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer contains a Heusler alloy represented by the following General Formula (1):
Co 2 Fe α X β (1)
(in Formula (1), X represents one or more elements selected from the group consisting of Mn, Cr, Si, Al, Ga and Ge, and α and β represent numbers that satisfy 2.3≤α+β, α<β, and 0.5<α<1.9).
2. The magnetoresistance effect element according to claim 1 ,
wherein the Heusler alloy is an alloy represented by the following General Formula (2):
Co 2 Fe α Ga γ Y β-γ (2)
(in Formula (2), Y represents one or more elements selected from the group consisting of Mn, Cr, Si, Al and Ge, and α, β and γ represent numbers that satisfy 2.3≤α+β, α<β, and 0.5<α<1.9, 0.1≤γ).
3. The magnetoresistance effect element according to claim 2 ,
wherein, in General Formula (2), β and γ represent numbers that satisfy 2×γ<β.
4. The magnetoresistance effect element according to claim 1 ,
wherein the Heusler alloy is an alloy represented by the following General Formula (3):
Co 2 Fe α Ge δ Z β-δ (3)
(in Formula (3), Z represents one or more elements selected from the group consisting of Mn, Cr, Si, Al and Ga, and α, β and δ represent numbers that satisfy 2.3≤α+β, α<β, and 0.5<α<1.9, 0.1≤δ).
5. The magnetoresistance effect element according to claim 4 ,
wherein, in General Formula (3), β and δ represent numbers that satisfy 2×δ>β.
6. The magnetoresistance effect element according to claim 1 ,
wherein the Heusler alloy is an alloy represented by the following General Formula (4):
Co 2 Fe α Ga γ Ge δ (4)
(in Formula (4), α, γ and δ represent numbers that satisfy 2.3≤α+γ+δ, α<γ+δ, and 0.5<α<1.9, 0.1≤γ, 0.1≤δ).
7. The magnetoresistance effect element according to claim 6 ,
wherein, in General Formula (4), γ and δ represent numbers that satisfy γ<δ.
8. The magnetoresistance effect element according to claim 6 ,
wherein, in General Formula (4), α, γ and δ represent numbers that satisfy 2.3≤α+γ+δ<2.66.
9. The magnetoresistance effect element according to claim 8 ,
wherein, in General Formula (4), α, γ and δ represent numbers that satisfy 2.45<α+γ+δ<2.66.
10. The magnetoresistance effect element according to claim 6 ,
wherein, in General Formula (4), δ represents a number that satisfies 0.63<δ<1.26.
11. The magnetoresistance effect element according to claim 10 ,
wherein, in General Formula (4), δ represents a number that satisfies 0.84<δ<1.26.
12. The magnetoresistance effect element according to claim 1 ,
wherein the Heusler alloy is an alloy represented by the following General Formula (5):
Co 2 Fe α Ga γ Ge δ Mn ε (5)
(in Formula (5), α, γ, δ and ε represent numbers that satisfy 2.3≤α+γ+δ+ε, α<γ+δ+ε, and 0.5<α<1.9, 0.1≤γ, 0.1≤δ, 0.1≤ε).
13. The magnetoresistance effect element according to claim 12 ,
wherein, in General Formula (5), δ and ε represent numbers that satisfy δ<ε.
14. The magnetoresistance effect element according to claim 12 ,
wherein, in General Formula (5), c represents a number that satisfies 0.38<ε<0.76.
15. The magnetoresistance effect element according to claim 1 ,
wherein the non-magnetic layer contains Ag.
16. The magnetoresistance effect element according to claim 1 ,
wherein a NiAl layer containing a NiAl alloy is provided between the first ferromagnetic layer and the non-magnetic layer and between the second ferromagnetic layer and the non-magnetic layer.
17. The magnetoresistance effect element according to claim 16 ,
wherein the thickness t of the NiAl layer satisfies 0<t≤0.63 nm.
18. The magnetoresistance effect element according to claim 16 ,
wherein the NiAl alloy contains a larger amount of Ni than of Al.
19. The magnetoresistance effect element according to claim 16 ,
wherein the NiAl alloy contains a larger amount of Al than of Ni.
20. The magnetoresistance effect element according to claim 1 ,
wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer is a laminate including two or more ferromagnetic layers, and the ferromagnetic layer in contact with the non-magnetic layer among the two or more ferromagnetic layers has a higher Fe concentration than the ferromagnetic layer on the side opposite to the non-magnetic layer.
21. The magnetoresistance effect element according to claim 1 ,
wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer is a laminate including two or more ferromagnetic layers, the two or more ferromagnetic layers each contains Ge, and the ferromagnetic layer in contact with the non-magnetic layer among the two or more ferromagnetic layers has a lower Ge concentration than the ferromagnetic layer on the side opposite to the non-magnetic layer.
22. The magnetoresistance effect element according to claim 1 ,
wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer is a laminate including two or more ferromagnetic layers, the two or more ferromagnetic layers each contains Ga, and the ferromagnetic layer in contact with the non-magnetic layer among the two or more ferromagnetic layers has a higher Ga concentration than the ferromagnetic layer on the side opposite to the non-magnetic layer.
23. The magnetoresistance effect element according to claim 1 ,
wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer is a laminate including two or more ferromagnetic layers, and the ferromagnetic layer in contact with the non-magnetic layer among the two or more ferromagnetic layers has a higher regularity than the ferromagnetic layer on the side opposite to the non-magnetic layer.
24. The magnetoresistance effect element according to claim 1 ,
wherein, on at least one of the first ferromagnetic layer and the second ferromagnetic layer, a layer containing Ni is provided on the side opposite to the non-magnetic layer.
25. A Heusler alloy represented by the following General Formula (1):
Co 2 Fe α X β (1)
(in Formula (1), X represents one or more elements selected from the group consisting of Mn, Cr, Si, Al, Ga and Ge, and α and β represent numbers that satisfy 2.3≤α+β, α<β, and 0.5<α<1.9).