SOT-MRAM with Segmented Free Layer Domain Wall
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Solution Overview
Problem
Current magnetic memory devices face challenges in achieving high efficiency writing and thermal stability, particularly in miniaturized forms, due to limitations in magnetization direction control and resistance value differentiation in 2-terminal structures.
Innovation Solution
A magnetic memory device with a 2-terminal structural spin orbit torque magnetoresistive random access memory (SOT-MRAM) configuration, featuring a first and second MTJ element with overlapping structures, where the first fixed layer, non-magnetic layer, and free layer with perpendicular magnetic anisotropy allow for domain wall formation and movement, enabling efficient writing and reading by differing resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a 2-terminal structural MTJ element is used for magnetic memory, then the device structure is simplified and manufacturing is easier, but the writing efficiency and thermal stability deteriorate due to limitations in magnetization direction control
Solution Approach 1:
The free layer is divided into two separate free layers (first free layer and second free layer) with different magnetization directions. Each free layer can be independently controlled by spin-polarized current, enabling efficient writing operations while maintaining the simplified 2-terminal structure. This segmentation allows the device to overcome the writing efficiency limitation of conventional single-free-layer designs.
Solution Approach 2:
Different regions of the magnetic memory device are assigned different magnetic properties. The first free layer has magnetization perpendicular to the film plane, while the second free layer has magnetization parallel to the film plane. This local differentiation enables independent control of magnetization directions, improving writing efficiency and thermal stability without complicating the overall device structure.
2Ease of manufacture
If a 2-terminal structural MTJ element is used for magnetic memory, then the device structure is simplified, but the thermal stability deteriorates due to limitations in magnetization direction control
Solution Approach 1:
The free layer is divided into two separate free layers (first free layer and second free layer) with different magnetization directions. Each free layer can be independently controlled by spin-polarized current, enabling efficient writing operations while maintaining the simplified 2-terminal structure. This segmentation allows the device to overcome the writing efficiency limitation of conventional single-free-layer designs.
Solution Approach 2:
Different regions of the magnetic memory device are assigned different magnetic properties. The first free layer has magnetization perpendicular to the film plane, while the second free layer has magnetization parallel to the film plane. This local differentiation enables independent control of magnetization directions, improving writing efficiency and thermal stability without complicating the overall device structure.
3Area of moving object
If miniaturization is implemented in magnetic memory devices, then integration density is improved, but thermal agitation tolerance deteriorates
Solution Approach 1:
Different regions of the magnetic memory device are assigned different magnetic properties. The first free layer has magnetization perpendicular to the film plane, while the second free layer has magnetization parallel to the film plane. This local differentiation enables independent control of magnetization directions, improving writing efficiency and thermal stability without complicating the overall device structure.
Solution Approach 2:
The magnetic memory device uses a composite structure with multiple ferromagnetic layers (first fixed layer, first free layer, second free layer, second fixed layer) having different magnetic anisotropy characteristics. This composite structure provides enhanced thermal stability through the combined effect of perpendicular and in-plane magnetic anisotropy, allowing miniaturization while maintaining thermal agitation tolerance.
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 configuration enables high-speed, low-power writing and reading with improved thermal stability across a wide temperature range, enhancing the reliability and integration density of magnetic memory devices, particularly in miniaturized forms.
Implementation Method 1
A magnetoresistive element performing reading with vertical magnetization by the magnetoresistance effect
Implementation Method 2
2-terminal structural spin orbit torque magnetoresistive random access memory (SOT-MRAM)
Data Source
AI summary
A magnetic memory device includes a first fixed layer maintaining a particular magnetization direction, a first non-magnetic layer, a free layer having perpendicular magnetic anisotropy and a variable magnetization direction, a second non-magnetic layer, and a second fixed layer maintaining a separate particular magnetization direction that is opposite to the particular magnetization direction of the first fixed layer. A resistance value of a first magnetic tunnel junction (MTJ) element including the first fixed layer, the first non-magnetic layer, and the free layer is different from that of a second MTJ element that includes the second fixed layer, the second non-magnetic layer, and the free layer, based on a first portion of the free layer in the first MTJ and a second portion of the free layer in the second MTJ being separated by a domain wall.