Magnetic Sensor Thin Ru Capping Layer Free Layer Volume
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Solution Overview
Problem
The existing magnetic sensors in hard disk drives face a challenge in maximizing the available volume for the free layer due to the space required by the spacer layer, which affects the overall performance.
Innovation Solution
A magnetic sensor design featuring a composite layer with a free layer portion and a bias layer portion, both made of magnetic materials, and a continuous non-magnetic spacer layer that separates the shield layer from the composite layer, enhancing magnetic coupling between the shield and bias layers while minimizing coupling with the free layer, thereby optimizing the sensor's volume and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spacer layer is added to protect the free layer during manufacturing, then the free layer is protected from damage, but the available volume for the free layer is reduced
Solution Approach 1:
A thin capping layer of Ru (5-10 nm) is introduced as an intermediary protective layer between the free layer and the environment. This capping layer serves as the primary protective barrier during manufacturing processes such as high temperature annealing, allowing the spacer layer to be reduced or removed entirely, thereby maximizing the free layer volume while maintaining protection.
Solution Approach 2:
The thickness of the spacer layer is reduced from conventional dimensions to a minimal thickness (5-10 nm) or eliminated completely. By changing the parameter of spacer layer thickness, the available volume for the free layer is maximized while the thin capping layer provides sufficient protection during manufacturing processes.
2Volume of moving object
If the spacer layer thickness is reduced to increase free layer volume, then the available volume for the free layer increases, but the protection during high temperature annealing is compromised
Solution Approach 1:
The thin capping layer of Ru (5-10 nm) serves as the primary protective intermediary during high temperature annealing processes. This capping layer is specifically designed to protect the free layer from oxidation and damage during manufacturing, replacing the need for a thick spacer layer and thereby maximizing free layer volume.
Solution Approach 2:
The sensor structure employs a composite material approach by combining the free layer with a thin Ru capping layer. This composite structure provides both the functional magnetic properties of the free layer and the protective characteristics of the Ru capping layer, enabling thin or removed spacer layers while maintaining protection during annealing.
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 increases the available volume for the free layer, enhancing the sensor's performance by maintaining strong magnetic coupling between the shield and bias layers while maintaining weak coupling with the free layer, thus improving data reading capabilities.
Implementation Method 1
enhancing magnetic coupling between the shield and bias layers while minimizing coupling with the free layer
Implementation Method 2
protects the free layer during various manufacturing processes, such as high temperature annealing
Data Source
AI summary
A magnetic sensor for use in a data storage device is described. The magnetic sensor includes a composite layer comprising a free layer portion and a bias layer portion each comprising a magnetic material, a shield layer comprising a magnetic material, and a continuous spacer layer comprising a non-magnetic material, the spacer layer separating the shield layer from the composite layer such that the magnetic coupling between the shield layer and the bias layer portion is stronger than the magnetic coupling between the shield layer and the free layer portion. A disk drive comprising a rotatable magnetic recording disk and the slider including the magnetic sensor arranged with the magnetic recording disk is also described.