Self-Reference MTJ Storage Structure for Field-Free Switching
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Solution Overview
Problem
Existing magnetic random memory (MRAM) technologies face challenges with high power consumption, low read margin, and circuit integration due to the need for external magnetic fields for magnetization switching and low tunneling magnetoresistance.
Innovation Solution
A self-reference storage structure with three transistors and two magnetic tunnel junctions, utilizing spin-orbit coupling and controlled torque ratios for field-free magnetization switching, and an in-memory computing circuit with an asymmetric sense amplifier for high read margin and logic operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external applied magnetic field is used for magnetization switching, then magnetization switching can be achieved, but power consumption increases and read margin decreases
Solution Approach 1:
The patent extracts and eliminates the need for external magnetic fields from the magnetization switching process. By using spin-orbit coupling and field-free switching mechanisms, the external magnetic field component is removed, thereby reducing power consumption while maintaining reliable read margins through deterministic magnetization switching.
Solution Approach 2:
The patent replaces the magnetic field-based switching mechanism with a spin-orbit coupling-based mechanism. This substitution eliminates the need for external magnetic fields and replaces them with electric field-controlled spin torque, achieving lower power consumption and improved read margin through more efficient spin transfer torque and damping-like torque mechanisms.
2Reliability
If tunneling magnetoresistance is low, then device integration is improved, but read margin becomes insufficient
Solution Approach 1:
The patent changes the fundamental parameters of magnetization switching by using spin-orbit coupling and field-free switching mechanisms. This enables deterministic switching with improved read margin while maintaining compatibility with standard magnetic tunnel junction structures, thereby achieving better read margin without significantly increasing device complexity.
3Use of energy by moving object
If deterministic magnetization switching without external magnetic field is achieved, then power consumption decreases, but switching reliability may be compromised
Solution Approach 1:
The patent employs composite material structures including spin-orbit coupling layers combined with ferromagnetic layers having perpendicular anisotropy. This composite structure enables deterministic magnetization switching through spin transfer torque and damping-like torque mechanisms, achieving both low power consumption and high switching reliability through the synergistic effects of different material properties.
Solution Approach 2:
The patent implements field-free switching mechanisms that provide intrinsic feedback control for deterministic magnetization switching. By utilizing spin-orbit coupling and perpendicular magnetic anisotropy, the system achieves self-regulated switching behavior that ensures reliable magnetization reversal without external magnetic fields, maintaining both low power consumption and high switching reliability.
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
Achieves low power consumption, fast switching, and high read reliability with improved circuit integration by eliminating the need for external magnetic fields and enhancing read margin through deterministic magnetization switching.
Implementation Method 1
both include: a spin-orbit coupling layer, a ferromagnetic free layer, a tunneling layer, a ferromagnetic reference layer and a top electrode
Implementation Method 2
injecting a current to spin-orbit coupling layers of the first magnetic tunnel junction and the second magnetic tunnel junction through the word line, to achieve a deterministic magnetization switching
Implementation Method 3
the tunneling magnetoresistance of the magnetic tunnel junction is relatively low
Data Source
AI summary
A self-reference storage structure includes: three transistors, including a first transistor T1, a second transistor T2, and a third transistor T3; and two magnetic tunnel junctions, including a first magnetic tunnel junction MTJ0 and a second magnetic tunnel junction MTJ1. The first magnetic tunnel junction MTJ0 is connected in series between the first transistor T1 and the second transistor T2, and the second magnetic tunnel junction MTJ1 is connected in series between the second transistor T2 and the third transistor T3. When the first transistor T1, the second transistor T2 and the third transistor T3 are turned on, one-bit binary information is written; and when data is stored, one-bit binary write can be implemented only by applying an unidirectional current pulse.