MAGNETORESISTANCE EFFECT DEVICE, MAGNETIC HEAD, MAGNETIC RECORDING SYSTEM, AND MAGNETIC RANDOM ACCESS MEMORY

Abstract

A CPP type magnetoresistance effect device having a synthetic ferri-pinned spin valve structure including a buffer layer, pinned ferromagnetic layer, nonmagnetic metal intermediate layer, and free ferromagnetic layer and having a free ferromagnetic layer made a specific composition of CoFeAl or CoMnAl, the buffer layer comprising an amorphous metal bottom layer and a nonmagnetic metal top layer. This magnetoresistance effect device increases the output ΔRA, reduces the coercivity Hc and the amount of shift Hin from a zero magnetic field to increase the sensitivity, and increases the magnetic field Hua of the resistance half point to increase the pin stability. A magnetic head, magnetic recording system, and magnetic random access memory using this magnetoresistance effect device are also disclosed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:

FIG. 1 is a cross-sectional view showing the layer configuration of a magnetoresistance effect device generally used as a conventional magnetic read head;

FIG. 2 is a graph schematically showing the change in resistance of a magnetoresistance effect device when running a sense current through the device to change the external magnetic field;

FIG. 3 is a cross-sectional view showing one example of the layer configuration according to a preferable aspect of the magnetoresistance effect device of the present invention;

FIG. 4 is a composition diagram showing the region of CoFeAl composition used for a free ferromagnetic layer of the present invention;

FIG. 5 is a composition diagram showing the region of CoMnAl composition used for a free ferromagnetic layer of the present invention;

FIG. 6 is a cross-sectional view showing an example of the structure of a tunnel type magnetoresistance effect device comprised of the magnetoresistance effect device of FIG. 3 with the nonmagnetic metal intermediate layer replaced by a nonmagnetic insulating layer;

FIG. 7 is a cross-sectional view showing an example of the structure of a dual-type magnetoresistance effect device comprised of two layers of the magnetoresistance effect device of FIG. 3;

FIG. 8 is a cross-sectional view showing an example of the structure of a magnetic head provided with a read head including the magnetoresistance effect device of the present invention;

FIG. 9 is a plan view showing an example of a magnetic recording system provided with a magnetic head using the magnetoresistance effect device of the present invention for the read head;

FIG. 10 is a perspective view schematically showing a current magnetic field type random access memory using the magnetoresistance effect device of the present invention; and

FIG. 11 is a perspective view schematically showing a spin injection type random access memory using the magnetoresistance effect device of the present invention.

Claims

1. A magnetoresistance effect device having a spin valve structure including a buffer layer at a bottommost layer, a pinned ferromagnetic layer above that, a nonmagnetic metal intermediate layer, and a free ferromagnetic layer, wherein said free ferromagnetic layer is comprised of one of the following (1) and (2): (1) a composition in the region of a CoFeAl ternary system composition diagram obtained by connecting a point A, point B, point C, point D, point E, point F, and point A by straight lines in that order for a point A (55,10,35), point B (50,15,35), point C (50,20,30), point D (55,25,20), point E (60,25,15), and point F (70,15,15) when expressing the coordinates of compositions as (Co content, Fe content, Al content [unit of each content being atm %]) and(2) a composition in the region of a CoMnAl ternary system composition diagram obtained by connecting a point A, point B, point C, point D, point E, point F, and point A by straight lines in that order for a point A (44,23,33), point B (48,25,27), point C (60,20,20), point D (65,15,20), point E (65,10,25), and point F (60,10,30) when expressing the coordinates of the compositions as (Co content, Mn content, Al content [unit of each content being atm %]),said buffer layer being comprised of a bottom layer of an amorphous metal buffer layer and a top layer of a nonmagnetic metal buffer layer.

2. A magnetoresistance effect device as set fort in claim 1, wherein said amorphous metal buffer layer is comprised of one of the following (a), (b), and (c):(a) one single metal of Ta, Ti, and Zr,(b) an amorphous alloy comprised of at least one ingredient of Fe, Co, Ni, and Cu and at least one ingredient of P, C, B, Si, Al, Ge, Be, Sn, In, Mo, W, Ti, Mn, Cr, Zr, Hf; and Nb, and(c) an amorphous alloy comprised of at least one ingredient of Ca, Mg, and Al and at least one ingredient of Zn and Cd,said nonmagnetic metal buffer layer comprising one of the following: Ru, Cu, Au, Ag, Rh, Ir, Pt, Pd, Os, Al, W, Nb, Mo, Tc, Ti, V, and Cr.

3. A magnetoresistance effect device as set forth in claim 1, wherein said pinned ferromagnetic layer is comprised of the composition of the above (1).

4. A magnetoresistance effect device as set forth in claim 1, wherein said spin valve structure is a so-called synthetic ferri-pinned structure comprised of, in order from the bottom, said buffer layer, antiferromagnetic layer, first pinned ferromagnetic layer, nonmagnetic coupling layer, second pinned ferromagnetic layer, nonmagnetic metal intermediate layer, free ferromagnetic layer, and protective layer.

5. A magnetoresistance effect device as set forth in claim 4, wherein said second pinned ferromagnetic layer is comprised of CoMnZ, where Z is at least one element of Al, Si, Ga, Ge, Cu, Mg, V, Cr, In, Sn, B, and Ni.

6. A magnetoresistance effect device as set forth in claim 4, wherein the device is a tunnel type replacing the nonmagnetic metal intermediate layer of said synthetic ferri-pinned spin valve structure with a nonmagnetic insulating intermediate layer.

7. A magnetoresistance effect device as set forth in claim 4, wherein the device has a dual-type synthetic ferri-pinned spin valve structure comprised of said buffer layer, a bottom laminated region where, among the component layers of said synthetic ferri-pinned spin valve structure, the antiferromagnetic layer to the free ferromagnetic layer are stacked in order from the bottom, and, on top of this, a top laminated region where the free ferromagnetic layer to the antiferromagnetic layer are stacked in order from the bottom in the reverse order from this, the two laminated regions being joined together sharing a free ferromagnetic layer.

8. A magnetoresistance effect device as set forth in claim 4 having a free ferromagnetic layer comprised of a CoMnAl composition of (2) or a CoMnZ composition, provided with a synthetic ferri-pinned spin valve structure, and provided between the free ferromagnetic layer and said nonmagnetic metal intermediate layer or nonmagnetic insulating intermediate layer with a diffusion prevention layer for preventing diffusion of Mn from the free ferromagnetic layer to said nonmagnetic metal intermediate layer or nonmagnetic insulating intermediate layer, said diffusion prevention layer comprised of one of the following (A) and (B): (A) a ferromagnetic material comprised of at least one metal of Co, Fe, and Ni or their alloys and(B) a nonmagnetic material comprised of at least one metal of Ti, Ta, W, Au, Pt, Mo, and Hf or their alloys.

9. A magnetoresistance effect device as set forth in claim 1, having a magnetoresistance change ΔRA ≧6.3 mΩμm2, a coercivity Hc≦5 Oe, a magnetic field Hua of the point where the resistance becomes half ≧1400 Oe, and an amount of shift Hin from a zero external magnetic field ≦20 Oe.

10. A magnetoresistance effect device as set forth in claim 1, wherein said buffer layer has a thickness of the amorphous metal buffer layer of at least 1 nm and the nonmagnetic metal buffer layer of at least 1 nm.

11. A magnetic head provided with a read head including a magnetoresistance effect device as set forth in claim 1.

12. A magnetic recording system provided with a magnetic head as set forth in claim 11 and a magnetic recording medium.

13. A magnetic random access memory of a current magnetic field recording type provided with a structure using a plurality of magnetoresistance effect devices as set forth in claim 1, arranging them at lattice points of a matrix comprised of a plurality of bit lines and a plurality of word lines, and connecting the plurality of bit lines and the plurality of word lines to the top electrodes and bottom electrodes of the plurality of magnetoresistance effect devices, magnetization inversion of said free ferromagnetic layer being induced by a current magnetic field generated by running a current through said bit lines and said word lines.

14. A magnetic random access memory of a spin injection type provided with a structure using a plurality of magnetoresistance effect devices as set forth in claim 1 and connecting a plurality of bit lines to top electrodes of said plurality of magnetoresistance effect devices, magnetization inversion of said free ferromagnetic layer being induced by running a spin polarized current through said bit lines.