Spin transfer torque magnetic memory device using magnetic resonance precession and the spin filtering effect

Abstract

The present invention relates to a magnetic memory device which additionally comprises a free magnetic layer constituting a horizontal direction variable magnetization layer having a fixed saturation magnetization value, whereby a switching current is markedly reduced as compared with conventional magnetic layers such that a high degree of integration of the device can be achieved and it is possible to lower a critical current density necessary for magnetization reversal thereby reducing the power consumption of the device. Also, a stray field effect occurring from a fixed magnetic layer is reduced such that a written magnetization data is thermally stable.

1 . A magnetic memory device comprising:
 a first fixed magnetic layer;   a first free magnetic layer; and   a second free magnetic layer,   wherein the first fixed magnetic layer is a thin layer formed of a material that has a fixed magnetization direction and that is magnetized in a perpendicular direction to a plane of the layer,   wherein the first free magnetic layer is a thin layer formed of a material that has a magnetization direction changed by a current applied from the outside and that is magnetized in a perpendicular direction to a plane of the layer,   wherein the second free magnetic layer is a thin layer formed of a material that has a magnetization direction changed by a current applied from the outside and that is magnetized in a horizontal direction to a plane of the layer, and   wherein a first non-magnetic layer and a second non-magnetic layer are disposed between the first fixed magnetic layer and the first free magnetic layer and between the first free magnetic layer and the second free magnetic layer, respectively.   
     
     
         2 . The magnetic memory device of  claim 1 , further comprising:
 a second fixed magnetic layer; and   a third non-magnetic layer between the second free magnetic layer and the second fixed magnetic layer, and   wherein the second fixed magnetic layer is a thin layer formed of a material that has a fixed magnetization direction opposite to the first fixed magnetic layer and that is magnetized in a perpendicular direction to a plane of the layer.   
     
     
         3 . The magnetic memory device of  claim 1 , wherein a saturation magnetization value of the material magnetized in the horizontal direction is in a range of 300˜2000 kA/m. 
     
     
         4 . The magnetic memory device of  claim 1  or  2 , wherein the first fixed magnetic layer and the second fixed magnetic layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof. 
     
     
         5 . The magnetic memory device of  claim 4 , wherein the first fixed magnetic layer and the second fixed magnetic layer are a multi-thin layer consisting of n stacked double layer (n≧1), respectively,
 wherein the double layer consists of an X layer and a Y layer, and 
 wherein the X layer and the Y layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Tb, Zr, Pt, Pd, and a mixture thereof. 
 
     
     
         6 . The magnetic memory device of  claim 1  or  2 , wherein at least one of the first fixed magnetic layer and the second fixed magnetic layer has an anti-magnetic structure consisting of a first magnetic layer, a non-magnetic layer and a second magnetic layer, and
 wherein the first magnetic layer and the second magnetic layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof. 
 
     
     
         7 . The magnetic memory device of  claim 6 , wherein at least one of the first magnetic layer and the second magnetic layer is a multi-thin layer consisting of n stacked double layer (n≧1),
 wherein the double layer consists of an X layer and a Y layer, and 
 wherein the X layer and the Y layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof. 
 
     
     
         8 . The magnetic memory device of  claim 1  or  2 , wherein at least one of the first fixed magnetic layer and the second fixed magnetic layer has an exchange biased anti-magnetic structure consisting of an antiferromagnetic layer, a first magnetic layer, a non-magnetic layer and a second magnetic layer,
 wherein the antiferromagnetic layer is formed of a material selected from a group consisting of Ir, Pt, Mn, and a mixture thereof, and 
 wherein the first magnetic layer and the second magnetic layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof. 
 
     
     
         9 . The magnetic memory device of  claim 8 , wherein at least one of the first magnetic layer and the second magnetic layer is a multi-thin layer consisting of n stacked double layer (n≧1),
 wherein the double layer consists of an X layer and a Y layer, and 
 wherein the X layer and the Y layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof. 
 
     
     
         10 . The magnetic memory device of  claim 1  or  2 , wherein the first fixed magnetic layer and the second fixed magnetic layer are formed of different materials from each other and have different multi-thin layer structures from each other. 
     
     
         11 . The magnetic memory device of  claim 1 , wherein the first free magnetic layer is formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof. 
     
     
         12 . The magnetic memory device of  claim 1 , wherein the first free magnetic layer is a multi-thin layer consisting of: a layer formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof; and a layer consisting of n stacked double layer (n≧1),
 wherein the double layer consists of an X layer and a Y layer, and 
 wherein the X layer and the Y layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, and Pd. 
 
     
     
         13 . The magnetic memory device of  claim 1 , wherein the second free magnetic layer is formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, and a mixture thereof. 
     
     
         14 . The magnetic memory device of  claim 1  or  2 , wherein the first non-magnetic layer, the second non-magnetic layer and the third non-magnetic layer are formed of different materials from each other, and
 wherein the first non-magnetic layer, the second non-magnetic layer and the third non-magnetic layer are each independently formed of a material selected from a group consisting of Ru, Cu, Al, Ta, Au, Ag, AlO x , MgO, TaO x , ZrO x , and a mixture thereof. 
 
     
     
         15 . The magnetic memory device of  claim 1  or  2 , wherein electrical conductivities of the first non-magnetic layer, the second non-magnetic layer and the third non-magnetic layer are higher than those of the first fixed magnetic layer, the first free magnetic layer, the second free magnetic layer and the second fixed magnetic layer. 
     
     
         16 . The magnetic memory device of  claim 1  or  2 , wherein electrical conductivities of the first non-magnetic layer, the second non-magnetic layer and the third non-magnetic layer are lower than those of the first fixed magnetic layer, the first free magnetic layer, the second free magnetic layer and the second fixed magnetic layer. 
     
     
         17 . The magnetic memory device of  claim 1 , further comprising: an upper electrode and a lower electrode supplying a current to a device.