Magnetic Memory Free Layer Segmentation for Thermal Stability
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Solution Overview
Problem
Magnetic memory devices face challenges in achieving high speed and low power consumption while maintaining thermal stability and efficient data storage, particularly in next-generation memory applications where traditional designs often require increased thickness for stability, leading to higher critical switching current densities.
Innovation Solution
A magnetic memory device structure is developed with a free layer comprising two magnetic layers and a nonmagnetic layer in between, where the product of the saturated magnetization and thickness of the first magnetic layer is less than half of the second magnetic layer, allowing for improved thermal stability and reduced critical switching current density without increasing thickness, using ferromagnetic materials with varying aluminum concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the thickness of the magnetic layer is increased to improve thermal stability, then thermal stability is improved, but the critical switching current density increases
Solution Approach 1:
The free layer is divided into two separate magnetic layers (first magnetic layer and second magnetic layer) with different saturated magnetization values. This segmentation allows each layer to contribute differently to the overall magnetic properties, achieving thermal stability through the combined effect while maintaining lower switching current density compared to a single thick layer.
Solution Approach 2:
The patent applies local quality by creating magnetic layers with non-uniform properties - specifically, the first magnetic layer has a different product of saturated magnetization and thickness compared to the second magnetic layer. This local variation in magnetic properties allows optimization of different regions for different functions: one layer provides stability while the other facilitates easier switching.
2Stability of the object's composition
If the thickness of the magnetic layer is increased to maintain thermal stability, then thermal stability is maintained, but the device complexity increases
Solution Approach 1:
Rather than using a single thick magnetic layer which would be structurally simple, the patent segments the free layer into two thinner magnetic layers. This segmentation achieves the desired thermal stability through the combined magnetic moments while maintaining relatively simple overall device structure and 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 configuration enhances thermal stability and reduces the critical switching current density, enabling efficient data storage with improved writing accuracy and stability, while maintaining low thickness, thus addressing the limitations of traditional designs.
Implementation Method 1
a resistance of the magnetic tunnel junction (MTJ) pattern may be changed by changing magnetization directions of the two magnetic substances
Implementation Method 2
a first magnetic layer adjacent the reference layer, a second magnetic layer spaced apart from the first magnetic layer and a nonmagnetic layer between the first and second magnetic layers
Data Source
AI summary
A magnetic memory device may include a tunnel barrier, a reference layer on a first side of the tunnel barrier, and a free layer on a second side of the tunnel barrier so that the tunnel barrier is between the reference and free layers. The free layer may include a first magnetic layer adjacent the tunnel barrier, a nonmagnetic layer on the first magnetic layer, and a second magnetic layer on the nonmagnetic layer. More particularly, the nonmagnetic layer may be between the first and second magnetic layers, and the first magnetic layer may be between the tunnel barrier and the second magnetic layer. A product of a saturated magnetization of the first magnetic layer and a thickness of the first magnetic layer may be less than a product of a saturated magnetization of the second magnetic layer and a thickness of the second magnetic layer. Related methods are also discussed.