Magnetoresistive effect element, magnetic head, sensor, high-frequency filter, and oscillator

1. A magnetoresistive effect element comprising:

a first ferromagnetic layer;

a second ferromagnetic layer; and

a spacer layer that is disposed between the first ferromagnetic layer and the second ferromagnetic layer,

wherein the spacer layer includes:

a nonmagnetic layer, and

at least one of

a first insertion layer that is disposed on a bottom surface of the nonmagnetic layer and

a second insertion layer that is disposed on a top surface of the nonmagnetic layer, and

wherein the first insertion layer and the second insertion layer include an Fe alloy that is expressed by General Formula (1):

Fe γ X 1-γ   (1),

where X denotes one or more elements selected from a group consisting of O, Al, Si, Ga, Mo, Ag, and Au, and

γ satisfies 0<γ<1,

wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer includes a Heusler alloy that is expressed by General formula (2):

Co 2 L α M β   (2),

where L denotes one or more elements selected from a group consisting of Mn and Fe,

M denotes one or more elements selected from a group consisting of Si, Al, Ga, and Ge,

0.7≤α≤1.6, and

0.65≤β,

wherein α and β in General formula (2) satisfy 2<α+β.

2. The magnetoresistive effect element according to claim 1 , wherein

γ in General Formula (1) satisfies 0.6≤γ≤0.9.

3. The magnetoresistive effect element according to claim 2 , wherein X in General formula (1) is one or more elements selected from a group consisting of Al, Si, and Ga.

4. The magnetoresistive effect element according to claim 3 , wherein α and β in General formula (2) satisfy:

0.85≤α≤1.55, and

0.75≤β≤1.25.

5. The magnetoresistive effect element according to claim 3 ,

wherein 0.2 nm≤t 1 ≤10 nm is satisfied where t 1 denotes a thickness of the first insertion layer, and

wherein 0.2 nm≤t 2 ≤10 nm is satisfied where t 2 denotes a thickness of the second insertion layer.

6. The magnetoresistive effect element according to claim 1 , wherein α and β in General formula (2) satisfy:

0.85≤α≤1.55, and

0.75≤β≤1.25.

7. The magnetoresistive effect element according to claim 1 ,

wherein 0.2 nm≤t 1 ≤10 nm is satisfied where t 1 denotes a thickness of the first insertion layer, and

wherein 0.2 nm≤t 2 ≤10 nm is satisfied where t 2 denotes a thickness of the second insertion layer.

8. The magnetoresistive effect element according to claim 1 ,

wherein α and β in General formula (2) further satisfy

α+β≤2.75.

9. A magnetic head comprising the magnetoresistive effect element according to claim 1 .

10. A sensor comprising the magnetoresistive effect element according to claim 1 .

11. A magnetoresistive effect element comprising:

a first ferromagnetic layer;

a second ferromagnetic layer; and

a spacer layer that is disposed between the first ferromagnetic layer and the second ferromagnetic layer,

wherein the spacer layer includes:

a nonmagnetic layer, and at least one of

a first insertion layer that is disposed on a bottom surface of the nonmagnetic layer and

a second insertion layer that is disposed on a top surface of the nonmagnetic layer,

wherein the first insertion layer and the second insertion layer include an Fe alloy that is expressed by General Formula (1):

Fe γ X 1-γ   (1),

where X denotes one or more elements selected from a group consisting of Al, Ga and Ag, and

γ satisfies 0.6≤γ≤0.9,

wherein the first insertion layer is continued from one side to the other side of the magnetoresistive effect element in a transverse direction of the magnetoresistive effect element,

wherein the second insertion layer is continued from one side to the other side of the magnetoresistive effect element in a transverse direction of the magnetoresistive effect element,

wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer includes a Heusler alloy that is expressed by General formula (2):

Co 2 L α M β   (2),

where L denotes one or more elements selected from a group consisting of Mn and Fe,

M denotes one or more elements selected from a group consisting of Si, Al, Ga, and Ge,

1<α,

0.65≤β, and

2≤α+β.

12. The magnetoresistive effect element according to claim 11 ,

wherein 0.2 nm≤t 1 ≤10 nm is satisfied where t 1 denotes a thickness of the first insertion layer, and

wherein 0.2 nm≤t 2 ≤10 nm is satisfied where t 2 denotes a thickness of the second insertion layer.

13. The magnetoresistive effect element according to claim 11 ,

wherein α and β in General formula (2) further satisfy

α+β≤2.75.

14. A magnetic head comprising the magnetoresistive effect element according to claim 11 .

15. A sensor comprising the magnetoresistive effect element according to claim 11 .

16. A magnetoresistive effect element comprising:

a first ferromagnetic layer;

a second ferromagnetic layer; and

a spacer layer that is disposed between the first ferromagnetic layer and the second ferromagnetic layer,

wherein the spacer layer includes:

a nonmagnetic layer, and

at least one of

a first insertion layer that is disposed on a bottom surface of the nonmagnetic layer and

a second insertion layer that is disposed on a top surface of the nonmagnetic layer, and

wherein the first insertion layer and the second insertion layer include an Fe alloy that is expressed by General Formula (1):

Fe γ X 1-γ   (1),

where X denotes one or more elements selected from a group consisting of Mo and Au, and

γ satisfies 0.6≤γ≤0.9, and

wherein at least one of the first ferromagnetic layer and the second ferromagnetic layer includes a Heusler alloy that is expressed by General formula (2):

Co 2 LαMβ  (2),

where L denotes one or more elements selected from a group consisting of Mn and Fe,

M denotes one or more elements selected from a group consisting of Si, Al, Ga, and Ge,

0.7≤α—1.6,

0.65≤β, and

2<α+β.

17. The magnetoresistive effect element according to claim 16 ,

wherein 0.2 nm≤t 1 ≤10 nm is satisfied where t 1 denotes a thickness of the first insertion layer, and

wherein 0.2 nm≤t 2 ≤10 nm is satisfied where t 2 denotes a thickness of the second insertion layer.

18. The magnetoresistive effect element according to claim 16 ,

wherein α and β in General formula (2) further satisfy

α+β≤2.75.

19. A magnetic head comprising the magnetoresistive effect element according to claim 16 .

20. A sensor comprising the magnetoresistive effect element according to claim 16 .