Magnetoresistance effect element
A magnetoresistance effect element has favorable symmetry of an MR ratio even if the sign of a bias voltage is different, which is capable of reversing magnetization to a current, which has a high MR ratio. A magnetoresistance effect element includes a laminate in which an underlayer, a first ferromagnetic metal layer, a tunnel barrier layer, and a second ferromagnetic metal layer are laminated in that order, wherein the underlayer is made of one or more selected from a group containing of TiN, VN, NbN, and TaN, or mixed crystals thereof, and wherein the tunnel barrier layer is made of a compound having a spinel structure and represented by the following composition formula (1). (1): A x Ga 2 O y where A is a non-magnetic divalent cation and represents a cation of at least one element selected from the group consisting of magnesium, zinc, and cadmium, x is a number that satisfies 0<x≤2, and y is a number that satisfies 0<y≤4.
1. A magnetoresistance effect element comprising a laminate in which:
an underlayer;
a first ferromagnetic metal layer;
a tunnel barrier layer; and
a second ferromagnetic metal layer are laminated in this order,
wherein:
the underlayer is made of one or more selected from a group consisting of TiN, VN, NbN, TaN, and a mixed crystal thereof,
the tunnel barrier layer is made of a compound having a spinel structure and represented by a composition formula (1) below,
A x Ga 2 O y (1)
where:
A is a non-magnetic divalent cation and represents a cation of at least one element selected from a group consisting of magnesium, zinc, and cadmium,
x is a number that satisfies 0<x≤2, and
y is a number that satisfies 0<y≤4, and
the tunnel barrier layer comprises:
a lattice-matched portion that lattice-matches with both of the first ferromagnetic metal layer and the second ferromagnetic metal layer; and
a non-lattice-matched portion that is free of a lattice-matching with at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer.
2. The magnetoresistance effect element according to claim 1 , wherein
A in the composition formula (1) is a cation of at least one element selected from a group consisting of magnesium and zinc, and
the underlayer is made of one or more selected from a group consisting of TiN, VN, TaN, and mixed crystals thereof.
3. A magnetoresistance effect element comprising a laminate in which:
an underlayer made of NbN;
a first ferromagnetic metal layer;
a tunnel barrier layer; and
a second ferromagnetic metal layer are laminated in this order,
wherein the tunnel barrier layer is made of a compound having a spinel structure and represented by a composition formula (1) below,
A x Ga 2 O y (1)
where:
A is a cadmium ion, and
x is a number that satisfies 0<x≤2, and
y is a number that satisfies 0<y≤4.
4. The magnetoresistance effect element according to claim 3 , wherein the tunnel barrier layer comprises:
a lattice-matched portion that lattice-matches with both of the first ferromagnetic metal layer and the second ferromagnetic metal layer; and
a non-lattice-matched portion that is free of a lattice-matching with at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer.
5. The magnetoresistance effect element according to claim 1 ,
wherein the tunnel barrier layer has a spinel structure in which an atomic arrangement is disordered.
6. The magnetoresistance effect element according to claim 1 ,
wherein a crystal lattice of either or both of the first ferromagnetic metal layer and the second ferromagnetic metal layer matches the tunnel barrier layer in a cubic-on-cubic structure.
7. The magnetoresistance effect element according to claim 2 ,
wherein a crystal lattice of either or both of the first ferromagnetic metal layer and the second ferromagnetic metal layer matches the tunnel barrier layer in a cubic-on-cubic structure.
8. The magnetoresistance effect element according to claim 3 ,
wherein a crystal lattice of either or both of the first ferromagnetic metal layer and the second ferromagnetic metal layer matches the tunnel barrier layer in a cubic-on-cubic structure.
9. The magnetoresistance effect element according to claim 4 ,
wherein a crystal lattice of either or both of the first ferromagnetic metal layer and the second ferromagnetic metal layer matches the tunnel barrier layer in a cubic-on-cubic structure.
10. The magnetoresistance effect element according to claim 5 ,
wherein a crystal lattice of either or both of the first ferromagnetic metal layer and the second ferromagnetic metal layer matches the tunnel barrier layer in a cubic-on-cubic structure.
11. The magnetoresistance effect element according to claim 1 ,
wherein at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer has magnetic anisotropy perpendicular to a lamination direction.
12. The magnetoresistance effect element according to claim 2 ,
wherein at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer has magnetic anisotropy perpendicular to a lamination direction.
13. The magnetoresistance effect element according to claim 3 ,
wherein at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer has magnetic anisotropy perpendicular to a lamination direction.
14. The magnetoresistance effect element according to claim 1 ,
wherein at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer is Co 2 Mn 1-a Fe a Al b Si 1-b (0≤a≤1, 0≤b≤1).