Graded Side Shield Gap Magnetoresistive Read Head
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Solution Overview
Problem
Existing magnetoresistive read heads with side shields face challenges in achieving high read utilization and sensitivity reduction in the skirt region of the read sensitivity distribution, leading to inadequate signal output and low signal-to-noise ratio.
Innovation Solution
The design includes magnetoresistive heads with side shields positioned at varying distances from the sensor structure, featuring tapered or stepped surfaces to optimize the gap between the side shields and the sensor, allowing for increased read output while reducing the skirt ratio by adjusting the distance from the air bearing surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the side shield is positioned close to the sensor structure to reduce the skirt region sensitivity, then the sensitivity reduction in the skirt region is improved, but the read utilization decreases and signal output becomes inadequate
Solution Approach 1:
The patent applies local quality by creating a non-uniform gap structure where the distance between the side shield and sensor structure varies along the air bearing surface. Specifically, the gap is smaller at certain regions to reduce skirt sensitivity and larger at other regions to maintain read utilization. This is achieved through tapered surfaces on the side shield or sensor structure, or through stepped surfaces that create distinct gap regions, allowing different portions of the structure to have different functional properties.
Solution Approach 2:
The patent transitions from a uniform one-dimensional gap structure to a two-dimensional variable gap structure by introducing tapering or stepping in the gap dimension. This dimensional change allows the gap distance to vary along the length of the side shield, enabling simultaneous optimization of skirt reduction and read output by having different gap distances at different positions.
2Productivity
If the gap between the free layer and side shield is increased to improve bias strength, then the read utilization improves, but the sensitivity reduction effect in the skirt region is hindered
Solution Approach 1:
The patent resolves this contradiction by making the gap distance local rather than uniform. The gap is configured to be smaller in regions where skirt sensitivity reduction is needed and larger in regions where read utilization is needed. This local differentiation allows each region to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent segments the gap structure into different regions with different gap distances. Through tapered surfaces or stepped surfaces, the gap is divided into zones: one zone with smaller gap for skirt reduction and another zone with larger gap for read utilization. This segmentation allows independent optimization of each functional zone.
3Ease of manufacture
If a uniform gap structure is used between side shield and sensor, then the manufacturing is simplified, but the balance between read utilization and skirt sensitivity reduction cannot be achieved
Solution Approach 1:
The patent changes the gap parameter from a constant uniform value to a variable value that changes along the length of the side shield. This is achieved through tapered surfaces that gradually change the gap distance or stepped surfaces that create discrete gap levels. While slightly more complex than uniform gaps, these structures can be fabricated using standard semiconductor manufacturing techniques and provide the necessary performance optimization.
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 read output and reduces noise interference, achieving a balance between increased read utilization and sensitivity reduction in the skirt region, improving recording density and signal quality.
Implementation Method 1
The read head of a hard disk drive includes a spin valve element utilizing a magnetoresistive effect. By sensing the relative magnetizations of two ferromagnetic thin films sandwiching an intermediate layer, magnetic information can be read from nanoscale magnets on a recording medium.
Implementation Method 2
The side shield read head includes a soft magnetic body in the track width direction of the spin valve element, thus leading to sensitivity reduction at the skirt region of the read sensitivity distribution in the track width direction. The skirt reduction of the read sensitivity distribution occurs because the spin valve element captures the magnetic field generated at the center part of the recording track, and the magnetic shield formed by a soft magnetic body absorbs the magnetic field generated by portions of the recording track other than the center part.
Data Source
AI summary
Embodiments of the present invention generally include magnetoresistive heads, such as read heads, having a sensor structure and side shields disposed adjacent to the sensor structure. The distance between the side shields and the sensor structure increase in a direction from an ABS in the off-track direction. The magnetoresistive heads may include tapered surfaces on the side shields or sensor structure, or may include stepped surfaces on the side shields or sensor structure.