Vertical spin orbit torque devices

Abstract

A magnetic device and method for programming the magnetic device are described. The magnetic device includes a plurality of magnetic junctions and at least one spin-orbit interaction (SO) active layer having a plurality of sides and an axis. The SO active layer(s) carry a current in direction(s) substantially perpendicular to the plurality of sides along the axis. Each of the magnetic junction(s) is adjacent to the sides and substantially surrounds a portion of the SO active layer. Each magnetic junction includes a free layer, a reference layer and a nonmagnetic spacer layer between the pinned and free layers. The SO active layer(s) exert a SO torque on the free layer due to the current passing through the SO active layer(s). The free layer is switchable between stable magnetic states. The free layer may be written using the current and, in some aspects, another current driven through the magnetic junction.

We claim: 
     
       1. A magnetic device comprising:
 at least one spin-orbit interaction (SO) active layer having a plurality of sides and an axis, the at least one SO active layer carrying a current in at least one direction substantially perpendicular to the plurality of sides along the axis; and 
 at least one magnetic junction, each of the at least one magnetic junction being adjacent to the plurality of sides, extending around the axis, and substantially surrounding a portion of the SO active layer, each of the at least one magnetic junction including a free layer, a reference layer and a nonmagnetic spacer layer, the nonmagnetic spacer layer being between the reference layer and the free layer; 
 a first line configured to drive a current through the SO active layer along the axis, the at least one SO active layer exerting a SO torque around the axis on the free layer due to the current passing through the at least one SO active layer along the axis, the free layer being switchable between a plurality of stable magnetic states; and 
 a second line configured to drive current through the at least one magnetic junction. 
 
     
     
       2. The magnetic device of  claim 1  wherein each of the at least one magnetic junction further includes:
 a reference layer; and 
 a nonmagnetic spacer layer, the nonmagnetic spacer layer being between the reference layer and the free layer. 
 
     
     
       3. The magnetic device of  claim 1  further comprising:
 a substrate, each of the at least one magnetic junction forming a nonzero angle with the substrate. 
 
     
     
       4. The magnetic device of  claim 3  wherein the nonzero angle is substantially ninety degrees. 
     
     
       5. The magnetic device of  claim 1  wherein each of the at least one magnetic junction has a substantially circular cross-section. 
     
     
       6. The magnetic device of  claim 1  wherein the plurality of stable magnetic states of the free layer are selected from a first stable axis along the at least one direction; a second stable state parallel to the plurality of sides and a radial direction substantially perpendicular to the plurality of sides. 
     
     
       7. The magnetic device of  claim 1  wherein the SO active layer has a first resistivity and is part of a line including a core having a second resistivity, the SO active layer substantially surrounding the core, the first resistivity being less than the second resistivity. 
     
     
       8. The magnetic device of  claim 1  wherein the at least one magnetic junction is a single magnetic junction and wherein the magnetic device further includes:
 a selection device coupled with the at least one SO active layer. 
 
     
     
       9. The magnetic device of  claim 8  wherein the selection device is selected from a planar transistor and a three-dimensional transistor. 
     
     
       10. The magnetic device of  claim 7  further comprising:
 a diode coupled with the reference layer. 
 
     
     
       11. The magnetic device of  claim 1  wherein the at least one magnetic junction is a plurality of magnetic junctions. 
     
     
       12. The magnetic device of  claim 11  further comprising:
 at least one isolation device interleaved with the plurality of magnetic junctions. 
 
     
     
       13. A magnetic device comprising:
 a plurality of spin-orbit interaction (SO) active layers, each of the plurality of SO active layers having a plurality of sides and an axis, each of the plurality of SO active layers carrying a current in at least one direction substantially perpendicular to the plurality of sides along the axis; 
 at least one magnetic junction coupled with each of the plurality of SO active layers, each of the at least one magnetic junction being adjacent to the plurality of sides extending around the axis, and substantially surrounding a portion each of the plurality of SO active layers, each of the at least one magnetic junction including a free layer, a reference layer and a barrier layer, the barrier layer being between the reference layer and the free layer; 
 a first line configured to drive a current through each of the plurality of SO active layers, each of the plurality of SO active layers exerting a SO torque along the axis on the free layer due to the current passing through each of the plurality of SO active layers along the axis, the free layer being switchable between a plurality of stable magnetic states, the plurality of stable magnetic states of the free layer being selected from a first stable axis along the at least one direction; a second stable state parallel to the plurality of sides and a radial direction substantially perpendicular to the plurality of sides; and 
 a plurality of lines coupled with the reference layer of the at least one magnetic junction, the plurality of lines being configured to drive current through the at least one magnetic junction. 
 
     
     
       14. A method for writing to at least one magnetic junction of a magnetic device comprising:
 driving, with a first line, a spin-orbit interaction (SO) write current through at least one SO active layer having a plurality of sides and an axis, the at least one SO active layer carrying the SO write current in at least one direction substantially perpendicular to the plurality of sides along the axis, the at least one magnetic junction, each of the at least one magnetic junction being adjacent to the plurality of sides, extending around the axis, and substantially surrounding a portion of the SO active layer, each of the at least one magnetic junction including at least a free layer, a reference layer and a nonmagnetic spacer layer, the nonmagnetic spacer layer being between the reference layer and the free layer, the at least one SO active layer exerting a SO torque along the axis on the free layer due to the SO write current passing through the at least one SO active layer along the axis; and 
 driving, with a second line, a spin transfer torque (STT) write current through the at least one magnetic junction. 
 
     
     
       15. The method of  claim 14  wherein each of the at least one magnetic junction further includes a reference layer and a nonmagnetic spacer layer, the nonmagnetic spacer layer being between the reference layer and the free layer. 
     
     
       16. The method of claim  15  14 further comprising:
 driving a the spin transfer torque (STT) write current through the at least one magnetic junction while the SO write current is driven through the SO active layer, a final magnetic state of the free layer being set by the STT write current. 
 
     
     
       17. The method of claim  15  14 further comprising:
 driving a the spin transfer torque (STT) write current through the at least one magnetic junction after the SO write current starts to be driven through the SO active layer. 
 
     
     
       18. The method of claim  15  14 further comprising:
 driving a the spin transfer torque (STT) write current through the at least one magnetic junction after the SO write current terminates.