Magnetic Stack Shield-to-Shield Spacing Reduction
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Solution Overview
Problem
Current magnetic sensors face challenges in increasing areal density and accurate data sensing due to magnetic instability and noise, primarily caused by the extension of antiferromagnetic structures to the air bearing surface, which increases physical and magnetic thickness.
Innovation Solution
A magnetic stack design featuring a ferromagnetic free layer, a synthetic antiferromagnetic structure, and a spacer layer, with the antiferromagnetic structure offset from the air bearing surface, and a shield layer configuration that reduces shield-to-shield spacing, allowing for a smaller physical thickness while maintaining magnetic stability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the antiferromagnetic structure is extended to the air bearing surface to provide magnetic stability, then the magnetic state stability is improved, but the shield-to-shield spacing increases and areal density decreases
Solution Approach 1:
The patent offsets the antiferromagnetic structure from the air bearing surface in the vertical dimension, positioning it at a predetermined distance rather than extending it to the surface. This dimensional repositioning maintains the magnetic stability function while reducing the vertical thickness of the magnetic stack, thereby decreasing shield-to-shield spacing and enabling higher areal density.
2Strength
If the antiferromagnetic structure extends to the air bearing surface, then magnetic pinning is enhanced, but the physical thickness of the magnetic stack increases
Solution Approach 1:
The patent applies local quality by concentrating the antiferromagnetic structure at a specific offset position from the air bearing surface rather than distributing it throughout the entire thickness. This localized positioning provides sufficient magnetic pinning strength at the critical interface while minimizing the overall physical thickness of the magnetic stack.
3Quantity of substance
If the shield-to-shield spacing is reduced to increase areal density, then the storage capacity is improved, but magnetic noise increases and sensing accuracy deteriorates
Solution Approach 1:
The patent introduces the offset antiferromagnetic structure as an intermediary element that mediates between the shields. By positioning this structure at a predetermined offset distance from the air bearing surface, it acts as a magnetic reference that reduces noise and improves sensing accuracy even when the overall shield-to-shield spacing is reduced for higher areal density.
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 design enhances areal density and data sensing accuracy by reducing magnetic thickness and noise, enabling more precise detection of magnetic fluctuations without compromising the stability of the magnetic state.
Implementation Method 1
a pinned layer proximate the AFM structure and coupled to the AFM structure
Implementation Method 2
a first shield layer proximate the AFM structure such that the AFM structure is between at least a portion of the first shield layer and the SAF structure
Data Source
AI summary
A magnetic stack is disclosed. The magnetic stack includes a magnetically responsive lamination that includes a ferromagnetic free layer, a synthetic antiferromagnetic (SAF) structure, and a spacer layer positioned between the ferromagnetic free layer and the SAF structure. The magnetically responsive lamination is separated from a sensed data bit stored in an adjacent medium by an air bearing surface (ABS). The stack also includes a first antiferromagnetic (AFM) structure coupled to the SAF structure a predetermined offset distance from the ABS, and a second AFM structure that is separated from the first AFM structure by a first shield layer.