Magnetic Sensor Narrow Trackwidth Read Gap Segmentation
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Solution Overview
Problem
The challenge in magnetic data recording is to reduce gap spacing while maintaining robust sensor performance and stability, as the thickness of sensor layers can only be reduced so much without adversely affecting performance.
Innovation Solution
A magnetic sensor design with a sensor stack comprising a first portion defining the track-width and a second portion extending beyond it, including a magnetic free layer, non-magnetic layer, and pinned layers with anti-parallel coupling and antiferromagnetic material, allowing for finer resolution and reduced track-width for increased data density, and removing antiferromagnetic material near the air bearing surface to minimize gap thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gap spacing of the magnetic sensor is decreased to increase linear data density, then data density is improved, but sensor performance and stability deteriorate
Solution Approach 1:
The sensor stack is divided into a first portion defining the track-width and a second portion extending beyond it, allowing differential treatment of regions. The first portion maintains full layer structure for performance while the second portion enables gap reduction, segmenting the sensor into functional zones that resolve the contradiction between data density and stability
Solution Approach 2:
Different regions of the sensor stack are given different properties: the first portion has the complete layered structure for optimal sensing performance, while the second portion has extended structure allowing reduced gap spacing. This local differentiation allows simultaneous achievement of high data density and maintained sensor stability
2Length of stationary object
If the thickness of sensor layers is reduced to decrease gap spacing, then gap spacing is improved, but sensor performance deteriorates
Solution Approach 1:
The sensor stack thickness is segmented into regions: the first portion maintains full layer thickness for performance while the second portion reduces thickness to minimize gap. This segmentation allows gap spacing reduction without compromising the sensing performance of the first portion
Solution Approach 2:
The solution moves from uniformly reducing thickness in one dimension to a two-dimensional approach where the first portion maintains thickness for performance while the second portion reduces thickness for gap minimization, achieving both goals through dimensional differentiation
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 achieves smaller dimensions and finer resolution, enabling decreased track-width for increased data density and reduced magnetic spacing, thereby enhancing sensor performance and stability.
Implementation Method 1
a layer of anti-ferromagnetic material exchange coupled with the second magnetic pinned layer
Implementation Method 2
A magnetoresistive sensor such as a Giant Magnetoresistive (GMR) sensor
Implementation Method 3
or a Tunnel Junction Magnetoresisive (TMR) sensor
Implementation Method 4
When a current flows through the coil, a resulting magnetic field causes a magnetic flux to flow through the write pole
Data Source
AI summary
A magnetic sensor having a first sensor stack portion that includes a free layer, non-magnetic spacer or barrier layer and a portion of a pinned layer structure. The sensor has second sensor stack portion formed over the first sensor stack portion. The second sensor stack portion include includes a second portion of the pinned layer structure and a layer of antiferromagnetic material formed over the. The first sensor stack portion is configured with a width and stripe height that define the functional width and strip height of the sensor, whereas the upper portion can be made wider and deeper without affecting sensor performance. Because the patterning of the first sensor stack portion is performed on a thinner structure than would be necessary to pattern the entire sensor stack, the patterning can be performed with smaller dimensions and increased resolution.