Vertical Spin-Orbit Torque Junctions for Lower-Current Switching
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Solution Overview
Problem
Conventional spin-orbit torque (SOT) magnetic memories face inefficiencies in switching the free layer, requiring high write currents and having a large footprint due to wasted spin current and limited scalability, especially when dealing with perpendicular magnetic moments.
Innovation Solution
The design incorporates vertical magnetic junctions with a spin-orbit interaction (SO) active layer carrying current perpendicular to its sides, surrounding each magnetic junction, which exerts SO torque on the free layer, allowing for efficient switching and reduced selection devices, optimized read and write operations, and potentially lower current densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional spin-orbit torque (SOT) magnetic memories use in-plane current through SO line to switch free layer, then switching can be achieved, but high write current is required and large footprint results from wasted spin current
Solution Approach 1:
The patent transitions from conventional in-plane current flow to vertical current flow through the SO active layer. The current is applied perpendicular to the magnetic junction plane, enabling spin-orbit torque to act vertically on the free layer magnetization. This dimensional change eliminates wasted spin current and reduces the required write current while improving switching efficiency.
Solution Approach 2:
The patent merges the SO active layer with the magnetic junction structure, where the SO active layer directly contacts and surrounds the free layer. This integration allows the spin current generated in the SO active layer to be efficiently transferred to the free layer without requiring separate current paths, eliminating wasted spin current and reducing footprint.
2Ease of operation
If conventional SOT memories use three-terminal device structure for write operations, then switching can be performed, but large footprint results from the additional terminal
Solution Approach 1:
The patent combines the read and write current paths into a single terminal structure. The same terminal that applies read current also applies write current vertically through the SO active layer. This merging eliminates the need for separate write terminals, reducing device footprint while maintaining full write operation capability.
Solution Approach 2:
The SO active layer serves multiple functions: it generates spin current for switching, provides a current path for both read and write operations, and acts as part of the magnetic junction structure. This multi-functionality eliminates the need for dedicated write terminals, reducing footprint while maintaining operational capability.
3Quantity of substance
If perpendicular magnetic moments are used in conventional SOT memories, then storage density can be improved, but limited scalability results from inability to utilize these moments effectively
Solution Approach 1:
The patent applies vertical current through the SO active layer, which generates spin-orbit torque that acts vertically on the perpendicular magnetization of the free layer. This enables effective utilization of perpendicular magnetic moments for high-density storage while maintaining scalability, as the vertical current path can be easily integrated into standard semiconductor fabrication processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the performance of magnetic devices by improving switching time, scalability, and reducing the breakdown of tunneling barriers, while allowing for separate optimization of read and write operations.
Implementation Method 1
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
Implementation Method 2
The SO active layer(s) exert a SO torque on the free layer due to the current passing through the SO active layer(s)
Data Source
AI summary
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 sidesalong 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.