Magnetic Storage Device Anchoring Layer Stabilization
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Solution Overview
Problem
Conventional MRAMs face challenges in maintaining stable write characteristics due to variations in recording layer shape and magnetization distribution, leading to increased power consumption and instability as devices are miniaturized, especially when the recording layers are asymmetric with respect to the easy and hard axes of magnetization.
Innovation Solution
A magnetic storage device design featuring a substrate with first and second wirings that cross each other, a recording layer with a planar shape sandwiched between them, and an anchoring layer comprising ferromagnetic and antiferromagnetic films, where the magnetizations of the ferromagnetic films are antiparallel and their product is smaller than that of the recording layer, to stabilize the magnetization state and reduce the influence of the anchoring layer on the recording layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the anchoring layer uses a single ferromagnetic film structure, then the structure is simple, but the magnetization distribution becomes unbalanced and write characteristics become unstable
Solution Approach 1:
The anchoring layer is segmented into multiple ferromagnetic films (first ferromagnetic film and second ferromagnetic film) with different magnetization directions. This segmentation allows each film to contribute differently to the overall magnetization, achieving a balanced total magnetization that stabilizes write characteristics while maintaining reasonable structural complexity.
2Ease of operation
If the recording layer shape is asymmetric, then the write current control becomes difficult and power consumption increases, but symmetric shapes have manufacturing variations
Solution Approach 1:
The invention changes the magnetic parameter (magnetization direction) of different regions within the anchoring layer to compensate for shape asymmetry in the recording layer. By adjusting the magnetization directions of the first and second ferromagnetic films, the system achieves stable write characteristics even when the recording layer has manufacturing-induced shape variations.
3Strength
If the anchoring layer has large magnetic moment, then the exchange coupling is strong, but the influence on the recording layer becomes excessive and destabilizes write operations
Solution Approach 1:
The first ferromagnetic film and second ferromagnetic film are designed with opposing magnetization directions that act as magnetic counterweights. Their combined magnetic moment is controlled to be less than or equal to the recording layer's magnetic moment, preventing excessive influence on the recording layer while maintaining sufficient exchange coupling for stable operation.
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 suppresses the variation in write current required to change the magnetization direction, resulting in a magnetic storage device with stable write characteristics and reduced power consumption, even as the shape of recording layers varies.
Implementation Method 1
the pin layer and the antiferromagnetic layer are exchange-coupled with each other and the magnetic moment of this ferromagnetic layer is fixed
Implementation Method 2
Magnetoresistive (MR) effect is a phenomenon that when a magnetic field is applied to a magnetic material, its electrical resistance varies
Implementation Method 3
its magnetization direction is varied by a synthetic magnetic field of a magnetic field arising from the first wiring and a magnetic field arising from the second wiring
Data Source
AI summary
A magnetic storage device stable in write characteristic is provided. A first nonmagnetic film is provided over a recording layer. A first ferromagnetic film is provided over the first nonmagnetic film and has a first magnetization and a first film thickness. A second nonmagnetic film is provided over the first ferromagnetic film. A second ferromagnetic film is provided over the second nonmagnetic film, is coupled in antiparallel with the first ferromagnetic film, and has a second magnetization and a second film thickness. An antiferromagnetic film is provided over the second ferromagnetic film. The sum of the product of the first magnetization and the first film thickness and the product of the second magnetization and the second film thickness is smaller than the product of the magnetization of the recording layer and the film thickness of the recording layer.