Magnetoresistive device and nonvolatile magnetic memory equipped with the same

Abstract

A fast and very low-power-consuming nonvolatile memory. A nonvolatile magnetic memory includes a high-output tunnel magnetoresistive device, in which spin-transfer torque is used for writing. A tunnel magnetoresistive device has a structure such that a ferromagnetic film of a body-centered cubic structure containing Co, Fe, and B, a MgO insulator film of a rock-salt structure oriented in (100), and a ferromagnetic film are stacked.

1 . A tunnel magnetoresistive device comprising an insulator film, and first and second ferromagnetic films between which the insulator film is disposed,
 wherein the first ferromagnetic film comprises a film of a body-centered cubic structure containing Co, Fe, and B, and wherein the insulator film comprises a MgO film of a rock-salt structure oriented in (100).   
     
     
         2 . The tunnel magnetoresistive device according to  claim 1 , wherein the second ferromagnetic film comprises a film of a body-centered cubic structure containing Co, Fe, and B. 
     
     
         3 . The tunnel magnetoresistive device according to  claim 1 , wherein the first ferromagnetic film has a Co-to-Fe composition ratio (atm %) of 50:50 to 70:30. 
     
     
         4 . The tunnel magnetoresistive device according to  claim 1 , comprising an orientation control film on which an antiferromagnetic film, a third ferromagnetic film, and a non-ferromagnetic film are sequentially stacked, wherein the first ferromagnetic film, the insulator film, and the second ferromagnetic film are sequentially stacked on the non-ferromagnetic film,
 wherein the magnetization direction of the third ferromagnetic film is fixed by the antiferromagnetic film, and wherein the third ferromagnetic film and the first ferromagnetic film are antiferromagnetically coupled via the non-ferromagnetic film.   
     
     
         5 . The tunnel magnetoresistive device according to  claim 4 , wherein, on the second ferromagnetic film, a second non-ferromagnetic film, a fourth ferromagnetic film, and a second antiferromagnetic film are sequentially stacked in mentioned order, wherein the magnetization direction of the fourth ferromagnetic film is fixed by the second antiferromagnetic film. 
     
     
         6 . The tunnel magnetoresistive device according to  claim 4 , wherein, on the second ferromagnetic film, a second non-ferromagnetic film and a fourth ferromagnetic film are sequentially stacked in mentioned order. 
     
     
         7 . The tunnel magnetoresistive device according to  claim 1 , comprising an orientation control film on which the first ferromagnetic film, the insulator film, and the second ferromagnetic film are sequentially stacked,
 wherein, on the second ferromagnetic film, a non-ferromagnetic film, a third ferromagnetic film, and an antiferromagnetic film are sequentially stacked,   wherein the magnetization direction of the third ferromagnetic film is fixed by the antiferromagnetic film, and wherein the third ferromagnetic film and the first ferromagnetic film are antiferromagnetically coupled via the non-ferromagnetic film.   
     
     
         8 . The tunnel magnetoresistive device according to  claim 7 , wherein, between the orientation control film and the first ferromagnetic film, a second antiferromagnetic film, a fourth ferromagnetic film, and a second non-ferromagnetic film are sequentially stacked in mentioned order, wherein the magnetization direction of the fourth ferromagnetic film is fixed by the second antiferromagnetic film. 
     
     
         9 . The tunnel magnetoresistive device according to  claim 7 , wherein, between the orientation control film and the first ferromagnetic film, a fourth ferromagnetic film and a second non-ferromagnetic film are sequentially stacked in mentioned order. 
     
     
         10 . A magnetic memory comprising a tunnel magnetoresistive device, and a switching element for controlling the ON/OFF of a current that flows through the tunnel magnetoresistive device,
 wherein the tunnel magnetoresistive device comprises an insulator film, and first and second ferromagnetic films between which the insulator film is disposed, wherein the first ferromagnetic film comprises a film of a body-centered cubic structure containing Co, Fe, and B, wherein the insulator film comprises a MgO film of a rock-salt structure oriented in (100).   
     
     
         11 . The magnetic memory according to  claim 10 , wherein the second ferromagnetic film comprises a film of a body-centered cubic structure containing Co, Fe, and B. 
     
     
         12 . The magnetic memory according to  claim 10 , wherein the first ferromagnetic film has a Co-to-Fe composition ratio (atm %) of 50:50 to 70:30. 
     
     
         13 . The magnetic memory according to  claim 10 , wherein magnetic information is recorded using spin-transfer torque. 
     
     
         14 . A magnetic random access memory comprising a plurality of magnetic memory cells and a means for selecting a desired magnetic memory cell, wherein the magnetic memory cells include a tunnel magnetoresistive device in which a first ferromagnetic film of a body-centered cubic structure containing Co, Fe, and B, a MgO insulator film of a rock-salt structure oriented in (100), and a second ferromagnetic film are stacked. 
     
     
         15 . The magnetic random access memory according to  claim 14 , wherein the second ferromagnetic film comprises a film of a body-centered cubic structure containing Co, Fe, and B. 
     
     
         16 . The magnetic random access memory according to  claim 14 , wherein the first ferromagnetic film has a Co-to-Fe composition ratio (atm %) of 50:50 to 70:30. 
     
     
         17 . The magnetic random access memory according to  claim 14 , wherein magnetic information is recorded using spin-transfer torque. 
     
     
         18 . The tunnel magnetoresistive device according to  claim 1 , wherein the composition ratio of Co is 0 to 50%. 
     
     
         19 . The magnetic memory according to  claim 10 , wherein the composition ratio of Co is 0 to 50%. 
     
     
         20 . The magnetic random access memory according to  claim 14 , wherein the composition ratio of Co is 0 to 50%.