Function Switchable SOT-MRAM via Magnetic Domain Wall Control
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Solution Overview
Problem
Spin-Orbit Torque Magnetic Random Access Memory (SOT-MRAM) faces limitations in directional magnetization switching due to random switching direction and lack of data security, requiring an in-plane magnetic field and only having rewritable functions, which are insecure against hacking.
Innovation Solution
A function switchable random access memory is developed, comprising two electromagnetic portions, a magnetic recording portion with a spin-orbit coupling layer and a magnetic tunnel junction, pinning regions, and cut-off regions, allowing for magnetization switching without an external magnetic field and enabling both rewritable and read-only functions through controlled spin current manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pure spin orbit torque is used for magnetization switching, then high-speed read/write capability is achieved, but the switching direction becomes random requiring an in-plane magnetic field
Solution Approach 1:
The patent introduces a magnetic domain wall as an intermediary carrier for information storage and manipulation. Instead of directly switching magnetization direction with spin-orbit torque, the spin current moves the magnetic domain wall to specific positions (pinning regions), which then determines the magnetization switching direction. This mediator approach converts the random switching into controlled directional switching.
Solution Approach 2:
The magnetic recording layer is segmented into multiple magnetic domains separated by domain walls. The patent creates a multi-domain structure where domain walls can be independently positioned and controlled. This segmentation allows the system to achieve directional control by moving domain walls to specific pinning regions rather than attempting to control the entire magnetization uniformly.
2Adaptability or versatility
If only rewritable function is provided, then memory flexibility is maintained, but data security against hacking is compromised
Solution Approach 1:
The patent makes the memory function dynamic by allowing the system to switch between read-only and rewritable modes. Through controlled annihilation of magnetic domain walls in specific regions, the system can permanently lock certain data areas to prevent rewriting, while maintaining rewriting capability in other areas. This dynamic functional change enables both data security (through read-only locking) and flexibility (through mode switching).
Solution Approach 2:
The patent implements data security by preliminarily creating read-only regions through selective domain wall annihilation before potential hacking attempts. By pre-establishing locked regions where domain walls are annihilated and cannot be recovered, the system proactively prevents unauthorized rewriting rather than reacting to security threats.
3Ease of operation
If an in-plane magnetic field is applied for directional switching, then magnetization direction control is achieved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces the mechanical/electromagnetic system of generating in-plane magnetic fields with a spin-tronic system. Instead of using external magnetic field generators or complex magnet structures, the system uses spin-orbit coupling to generate spin currents that manipulate magnetic domain walls. This substitution eliminates the need for additional magnetic field generation components while achieving precise directional control.
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
The solution achieves controlled magnetization switching and data security by generating a spin current to move magnetic domain walls, allowing users to set information as rewritable or read-only, enhancing data protection and application versatility.
Implementation Method 1
a spin current is generated by spin-orbit coupling
Implementation Method 2
generate two magnetic domains with magnetization pointing in opposite directions
Implementation Method 3
drive the magnetic domain wall to reciprocate under the action of the spin current, so as to achieve the switching of magnetization
Implementation Method 4
forms a tunneling magnetoresistance between the first magnetic layer and the second magnetic layer
Data Source
AI summary
Provided are a function switchable random access memory, including: two electromagnetic portions configured to connect a current; a magnetic recording portion between the two electromagnetic portions and including a spin-orbit coupling layer and a magnetic tunnel junction; a pinning region between each of the electromagnetic portions and the magnetic recording portion; a cut-off region on a side of each of the electromagnetic portions opposite to the pinning region, the spin-orbit coupling layer is configured to generate a spin current under an action of the current; the two electromagnetic portions is configured to generate two magnetic domains with magnetization pointing in opposite directions under an action of the spin current; the magnetic tunnel junction is configured to generate a magnetic domain wall based on the two opposite magnetic domains and is configured to drive the magnetic domain wall to reciprocate under the action of the spin current.