Magnetic tunnel junction element and magnetic memory
A magnetic tunnel junction element ( 10 ) includes a configuration in which a reference layer ( 14 ) that includes a ferromagnetic material, a barrier layer ( 15 ) that includes O, a recording layer ( 16 ) that includes a ferromagnetic material including Co or Fe, a first protective layer ( 17 ) that includes O, and a second protective layer ( 18 ) that includes at least one of Pt, Ru, Co, Fe, CoB, FeB, or CoFeB are layered.
1. A magnetic tunnel junction element, comprising:
a reference layer that comprises a ferromagnetic material;
a barrier layer that comprises oxygen;
a recording layer that comprises a ferromagnetic material comprising Co or Fe;
a first protective layer that comprises oxygen and has a thickness equal to or less than 5.0 nm;
a second protective layer being non-magnetic, comprising at least one of Co, Fe, CoB, FeB, or CoFeB and having a thickness from over 1.0 nm to less than 1.5 nm, and
a third protective layer, formed on the second protective layer and comprising atoms of Ru, Rh, Pd, Cu, Ir, Au, Hf, W, Zr, Nb, Mo, Ti, V, Cr, or an alloy thereof,
wherein
the second protective layer includes atoms which are same as atoms of the third protective layer and which are diffused from the third protective layer thereby preventing the second protective layer from being a magnetic layer;
the magnetic tunnel junction element is created as a stack of layers disposed in a following order: the reference layer, the barrier layer, the recording layer, the first protective layer and the second protective layer or as a stack of layers disposed in an inverted order.
2. The magnetic tunnel junction element according to claim 1 , wherein
the atoms comprise Ru atoms,
the second protective film includes Ru, and
the third protective film comprises Ru.
3. The magnetic tunnel junction element according to claim 1 , wherein
a direction of magnetization of the recording layer is perpendicular to an interface between the recording layer and the barrier layer or the first protective layer, with which the recording layer comes into contact, due to a magnetic anisotropy of the interface.
4. The magnetic tunnel junction element according to claim 2 , wherein
a direction of magnetization of the recording layer is perpendicular to an interface between the recording layer and the barrier layer or the first protective layer, with which the recording layer comes into contact, due to a magnetic anisotropy of the interface.
5. The magnetic tunnel junction element according to claim 1 , wherein
at least one of a junction surface between the reference layer and the barrier layer, a junction surface between the barrier layer and the recording layer, or a junction surface between the recording layer and the first protective layer is a junction surface of which an area is smaller than an area of a circle having a diameter of 30 nm.
6. A magnetic memory, comprising:
a storage cell comprising the magnetic tunnel junction element according to claim 1 ;
a write circuit that selects the storage cell and writes data into the storage cell; and
a read circuit that selects the storage cell and reads data from the storage cell.
7. A magnetic tunnel junction element, comprising:
a reference layer that comprises a ferromagnetic material;
a barrier layer that comprises oxygen;
a recording layer that comprises a ferromagnetic material comprising Co or Fe;
a first protective layer that comprises oxygen; and
a second protective layer,
wherein
the magnetic tunnel junction element is created as a stack of layers disposed in a following order: the reference layer, the barrier layer, the recording layer, the first protective layer and the second protective layer or as a stack of layers disposed in an inverted order,
a direction of magnetization of the recording layer is perpendicular to an interface between the recording layer and the barrier layer and the first protective layer, with which the recording layer comes into contact, due to a magnetic anisotropy of the interface,
the second protective layer comprises at least one of Co, Fe, CoB, FeB, or CoFeB,
the second protective layer has magnetism, and
the magnetic tunnel junction element further comprises: a non-magnetic layer formed on the second protective layer; and a ferromagnetic layer formed on the non-magnetic layer and magnetized in a direction parallel and opposite to a direction of magnetization of the second protective layer.
8. The magnetic tunnel junction element according to claim 7 , wherein
the second protective layer has a thickness of from over 1.5 nm to 3.5 nm.
9. The magnetic tunnel junction element according to claim 8 , wherein
a direction of magnetization of the recording layer is perpendicular to an interface between the recording layer and the barrier layer or the first protective layer, with which the recording layer comes into contact, due to a magnetic anisotropy of the interface.
10. The magnetic tunnel junction element according to claim 7 , wherein
at least one of a junction surface between the reference layer and the barrier layer, a junction surface between the barrier layer and the recording layer, or a junction surface between the recording layer and the first protective layer is a junction surface of which an area is smaller than an area of a circle having a diameter of 30 nm.
11. A magnetic memory, comprising:
a storage cell comprising the magnetic tunnel junction element according to claim 7 ;
a write circuit that selects the storage cell and writes data into the storage cell; and
a read circuit that selects the storage cell and reads data from the storage cell.