Three-dimensional (3d) magnetic memory devices comprising a magnetic tunnel junction (mtj) having a metallic buffer layer

Abstract

A magnetic memory device includes a cylindrical core; a plurality of layers surrounding the cylindrical core; a first terminal connected to a first end of the cylindrical core; and a second terminal connected to a second end of the cylindrical core, opposite the first end, wherein the first terminal is configured to receive a first current flowing radially from the cylindrical core through the plurality of layers, the first current imparting a torque on, at least, a magnetization of an inner layer of the plurality of layers.

1 . A magnetic memory device, comprising:
 a cylindrical core;   a plurality of layers surrounding the cylindrical core;   a first terminal connected to a first end of the cylindrical core; and   a second terminal connected to a second end of the cylindrical core, opposite the first end, wherein the first terminal is configured to receive a first current flowing radially from the cylindrical core through the plurality of layers, the first current imparting a torque on, at least, a magnetization of an inner layer of the plurality of layers.   
     
     
         2 . The magnetic memory device of  claim 1 , wherein the magnetization of the inner layer changes from a first direction to a second direction when the first current satisfies a threshold. 
     
     
         3 . The magnetic memory device of  claim 1 , wherein the second terminal is configured to receive a second current, imparting a Spin Hall Effect (SHE) around a circumference of the cylindrical core. 
     
     
         4 . The magnetic memory device of  claim 3 , wherein the SHE imparted around the circumference of the cylindrica core contributes to the torque imparted on the magnetization of the inner layer of the plurality of layers. 
     
     
         5 . The magnetic memory device of  claim 3 , wherein the magnetization of the inner layer is in a first chirality, and the SHE imparted around the circumference of the cylindrical core has a second chirality that is opposite to the first chirality. 
     
     
         6 . The magnetic memory device of  claim 1 , wherein the plurality of layers comprise a first ferromagnetic layer, a spacer layer, and a second ferromagnetic layer. 
     
     
         7 . The magnetic memory device of  claim 6 , wherein the inner layer is the first ferromagnetic layer. 
     
     
         8 . The magnetic memory device of  claim 6 , wherein:
 the first ferromagnetic layer surrounds the cylindrical core;   the spacer layer surrounds the first ferromagnetic layer; and   the second ferromagnetic layer surrounds the spacer layer.   
     
     
         9 . The magnetic memory device of  claim 8 , wherein the first ferromagnetic layer is a storage layer and the second ferromagnetic layer is a reference layer. 
     
     
         10 . The magnetic memory device of  claim 9 , further comprises a metallic buffer layer disposed between the cylindrical core and the first ferromagnetic layer. 
     
     
         11 . The magnetic memory device of  claim 10 , wherein the metallic buffer layer comprises tantalum or tantalum nitride. 
     
     
         12 . The magnetic memory device of  claim 8 , wherein the first ferromagnetic layer is a reference layer and the second ferromagnetic layer is a storage layer. 
     
     
         13 . The magnetic memory device of  claim 12 , further comprises a metallic buffer layer disposed between the spacer layer and the second ferromagnetic layer. 
     
     
         14 . The magnetic memory device of  claim 8 , further comprising a third terminal connected to the second ferromagnetic layer. 
     
     
         15 . The magnetic memory device of  claim 14 , wherein the third terminal is configured to read out a stored memory state of the magnetic memory device. 
     
     
         16 . The magnetic memory device of  claim 14 , wherein the third terminal is configured to receive the first current flowing radially from the cylindrical core through the plurality of layers. 
     
     
         17 . The magnetic memory device of  claim 1 , wherein the cylindrical core is a non-magnetic metal. 
     
     
         18 . A magnetic memory device, comprising:
 a cylindrical core;   a first ferromagnetic layer surrounds the cylindrical core;   a spacer layer surrounds the first ferromagnetic layer; and   a second ferromagnetic layer surrounds the spacer layer, wherein the second ferromagnetic layer is configured to receive a current flowing radially from the second ferromagnetic layer towards the cylindrical core, the current imparting a torque on, at least, magnetizations of the first ferromagnetic layer and the second ferromagnetic layer.   
     
     
         19 . The magnetic memory device of  claim 18 , further comprises a metallic buffer layer disposed between the cylindrical core and the first ferromagnetic layer. 
     
     
         20 . The magnetic memory device of  claim 18 , further comprises a metallic buffer layer disposed between the spacer layer and the second ferromagnetic layer.