Magnetic Head Closure Layers for Shield Noise Reduction
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Solution Overview
Problem
Magnetic head read sensors experience noise interference due to domain wall movement in shield layers, which is not effectively addressed by existing methods that increase complexity and cost or require difficult fabrication techniques.
Innovation Solution
The implementation of magnetic closure layers, spaced from the shield layers by non-magnetic gaps, creates a magnetic environment that stabilizes edge domains and minimizes domain wall movement, reducing noise interference at the read sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If domain wall movement in shield layers is addressed by existing methods, then noise interference at read sensor is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
A non-magnetic spacer layer is introduced as an intermediary between the magnetically permeable closure layer and the shield layer. This spacer acts as a magnetic barrier that prevents magnetic flux from the closure layer from directly coupling with the shield layer, thereby reducing domain wall movement-induced noise without requiring complex modifications to the shield structure itself
Solution Approach 2:
The magnetic shielding system is segmented into distinct functional layers: the magnetically permeable closure layer for flux containment, the non-magnetic spacer layer for magnetic isolation, and the shield layer for noise reduction. This segmentation allows each layer to perform its specific function independently, simplifying the overall design while effectively addressing noise interference
2Object-affected harmful factors
If domain wall movement in shield layers is addressed by existing methods, then noise interference at read sensor is reduced, but fabrication difficulty increases
Solution Approach 1:
The magnetic shielding system is segmented into distinct functional layers: the magnetically permeable closure layer for flux containment, the non-magnetic spacer layer for magnetic isolation, and the shield layer for noise reduction. This segmentation allows each layer to perform its specific function independently, simplifying the overall design while effectively addressing noise interference
Solution Approach 2:
The magnetic permeability parameter is utilized to differentiate layer functions: the closure layer has high permeability for flux containment, while the spacer layer has low permeability for magnetic isolation. This parameter-based differentiation enables straightforward fabrication processes where layers are deposited with specific magnetic properties, avoiding complex fabrication requirements
3Object-affected harmful factors
If shield layer structure is modified to stabilize edge domains, then noise interference is reduced, but manufacturing cost increases
Solution Approach 1:
A non-magnetic spacer layer is introduced as an intermediary between the magnetically permeable closure layer and the shield layer. This spacer acts as a magnetic barrier that prevents magnetic flux from the closure layer from directly coupling with the shield layer, thereby reducing domain wall movement-induced noise without requiring complex modifications to the shield structure itself
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 approach improves data retrieval accuracy by reducing stray magnetic fields interpreted as noise, without modifying existing shield structures, thus simplifying fabrication and reducing costs.
Implementation Method 1
magnetic closure layers (e.g., soft magnetic or other highly magnetically permeable layers such as NiFe) that are sandwiched about but spaced (i.e., magnetically isolated) from the first and second magnetic shields of the read portion of a magnetic head by first and second respective closure gaps
Implementation Method 2
The closure layers create a magnetic environment for the shield edges that more closely resembles the interior of the shield, thereby minimizing or at least reducing the number of unstable edge domains and limiting subsequent domain wall movement
Implementation Method 3
first and second respective nonmagnetic gap layers (e.g., Al2O3 or SiO2) that are sandwiched about but spaced from the first and second magnetically permeable closure layers by first and second respective nonmagnetic gap spaces
Implementation Method 4
an MR sensor positioned above the second read gap layer... Some MR sensors operate on the basis of the anisotropic MR (AMR) effect in which an MR element resistance varies as the square of the cosine of the angle between the magnetization of the MR element and the direction of sense current flowing through the MR element
Implementation Method 5
Another type of MR sensor is the giant MR (GMR) sensor that manifests the GMR effect. In GMR sensors, the resistance of the MR sensing layer(s) varies as a function of the spin-dependent transmission of the conduction electrons between magnetic layers separated by a non-magnetic layer (spacer)
Data Source
AI summary
Systems and methods that serve to limit the generation of stray magnetic fields by moving domain walls of magnetic shields of a magnetic head that would otherwise be received and interpreted as noise at the read sensor of the magnetic head. The utilities disclose use of first and second magnetic “closure” layers (e.g., soft magnetic layers) disposed about but spaced (i.e., magnetically isolated) from the first and second magnetic shields of the read portion of a magnetic head by first and second respective “closure” gaps (e.g., provided by any appropriate non-magnetic, high magnetic permeability material(s)). The closure layers create a magnetic environment for the shield edges that more closely resembles the interior of the shield, thereby minimizing or at least reducing the number of unstable edge domains and limiting subsequent domain wall movement.