Magnetoresistive Element Shield Exchange Coupling Read Gap
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Solution Overview
Problem
Existing magnetoresistive elements face challenges in reducing read gap length while maintaining high sensitivity and output, particularly in directing ferromagnetic layer magnetizations antiparallel without relying on antiferromagnetic coupling through the spacer layer, which limits material and thickness options and complicates heat treatment requirements.
Innovation Solution
A magnetoresistive element with a specific shield and exchange coupling layer configuration, including a nonmagnetic conductive underlayer, antiferromagnetic layers, and magnetization controlling layers, allows for antiparallel magnetization direction of free layers without antiferromagnetic coupling, enabling reduced read gap length and improved exchange coupling magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If antiferromagnetic coupling through the spacer layer is used to direct ferromagnetic layer magnetizations antiparallel, then the magnetization directions are stabilized, but the material and thickness options for the spacer layer are limited and heat treatment requirements are complicated
Solution Approach 1:
The patent extracts the antiferromagnetic coupling function from the spacer layer and relocates it to dedicated exchange coupling shield layers positioned between the read shield portions and the magnetoresistive stack. This separation allows the spacer layer to focus solely on its original function while the exchange coupling function is performed by specialized layers with optimized properties, thereby resolving the contradiction between stability and manufacturing flexibility.
Solution Approach 2:
The patent introduces exchange coupling shield layers as intermediary structures that mediate the exchange coupling function. These shield layers contain antiferromagnetic layers that provide the necessary exchange coupling to the ferromagnetic layers, acting as a mediator that stabilizes magnetization directions without imposing the material and thickness constraints that would otherwise be required of the spacer layer.
2Quantity of substance
If read gap length is reduced to increase recording density, then higher recording density is achieved, but the structure becomes more complex with additional exchange coupling shield layers
Solution Approach 1:
The exchange coupling shield layers serve multiple functions: they provide exchange coupling to stabilize magnetization directions, they act as magnetic shields to control magnetic field distribution, and they enable reduced read gap length for higher recording density. By combining these functions into single structures, the patent achieves high recording density without proportionally increasing overall device complexity.
Solution Approach 2:
The patent addresses the read gap length constraint by operating in the vertical dimension (adding exchange coupling shield layers above and below the magnetoresistive stack) rather than increasing horizontal dimensions. This allows the read gap to be reduced in the critical horizontal direction while managing complexity through vertical layering, effectively trading vertical space for horizontal performance.
3Length of moving object
If exchange coupling shield layers are added to enable antiparallel magnetization without spacer layer coupling, then read gap length can be reduced, but the number of layers and structural complexity increases
Solution Approach 1:
The patent segments the exchange coupling function from the spacer layer function and implements it through dedicated exchange coupling shield layers. Each shield layer is further segmented into multiple sub-layers (ferromagnetic layer, nonmagnetic layer, antiferromagnetic layer) that work together to provide the exchange coupling effect. This segmentation allows for independent optimization of each layer's properties while achieving the overall goal of reduced read gap length.
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 a significant reduction in read gap length, stabilizes magnetization directions, and enhances the performance of the magnetoresistive element by allowing antiparallel magnetization without material or thickness limitations, improving sensitivity and output.
Implementation Method 1
a first exchange coupling shield layer disposed between the first read shield portion and the magnetoresistive element, the first exchange coupling shield layer including: a nonmagnetic conductive underlayer disposed on the first read shield portion; a first antiferromagnetic layer disposed on the underlayer
Implementation Method 2
a magnetoresistive element (hereinafter, also referred to as MR element) for reading
Implementation Method 3
a TMR (tunneling magnetoresistive) element utilizing a tunneling magnetoresistive effect
Data Source
AI summary
A first shield portion located below an MR stack includes a first main shield layer, a first antiferromagnetic layer, and a first magnetization controlling layer including a first ferromagnetic layer exchange-coupled to the first antiferromagnetic layer. A second shield portion located on the MR stack includes a second main shield layer, a second antiferromagnetic layer, and a second magnetization controlling layer including a second ferromagnetic layer exchange-coupled to the second antiferromagnetic layer. The MR stack includes two free layers magnetically coupled to the two magnetization controlling layers. Only one of the two magnetization controlling layers includes a third ferromagnetic layer that is antiferromagnetically exchange-coupled to the first or second ferromagnetic layer through a nonmagnetic middle layer. The first shield portion includes an underlayer disposed on the first main shield layer, and the first antiferromagnetic layer is disposed on the underlayer.