Magnetic Seed and Cap Layers for Reduced Shield Spacing
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Solution Overview
Problem
In magnetic recording heads, the shield-to-shield spacing is limited by the seed and cap layers, hindering the reduction of stray magnetic field shielding and linear density of magnetic sensors.
Innovation Solution
Incorporating a magnetic seed layer and/or cap layer with specific properties, such as NiFe or NiFeNb, to reduce the effective shield-to-shield spacing while maintaining or enhancing pinning field and stability, allowing for thinner physical shield-to-shield spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the shield-to-shield spacing is reduced to improve shielding performance, then the linear density of magnetic transitions increases, but the seed and cap layers occupy a large proportion of the total stack thickness, limiting the reduction of shield-to-shield spacing
Solution Approach 1:
The patent changes the magnetic properties of the seed and cap layers by making them magnetic rather than nonmagnetic. This parameter change allows these layers to contribute to shielding functionality, effectively reducing the shield-to-shield spacing while maintaining adequate shielding performance. The magnetic seed and cap layers are configured to have magnetization vectors that provide shielding similar to traditional shields.
Solution Approach 2:
The patent makes the seed and cap layers serve multiple functions: they still provide their traditional functions of facilitating magnetization alignment and protecting the sensor, while also contributing to shielding against stray magnetic fields. This multi-functionality allows the same layers to reduce shield-to-shield spacing without compromising shielding effectiveness.
2Length of stationary object
If the seed and cap layers are made magnetic to reduce shield-to-shield spacing, then the effective shield-to-shield spacing decreases, but the complexity of the magnetic sensor structure increases
Solution Approach 1:
The patent modifies the magnetic properties of existing seed and cap layers, changing them from nonmagnetic to magnetic materials. This parameter change enables the layers to function as shields while maintaining their structural roles, thereby reducing effective shield-to-shield spacing without requiring entirely new structural components.
Solution Approach 2:
The patent merges the shielding function with the existing seed and cap layers by making them magnetic. Instead of adding separate shielding components, the invention combines the magnetization alignment function and shielding function into the same layers, reducing overall structural complexity while achieving the desired spacing reduction.
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 increases the linear density of magnetic transitions and improves shielding from adjacent bits, enhancing the magnetic stability and performance of the sensor.
Implementation Method 1
A typical MR sensor configuration includes a multilayered structure formed of a nonmagnetic layer positioned between a synthetic antiferromagnet (SAF) and a ferromagnetic free layer, or between two ferromagnetic free layers. The resistance of the MR sensor depends on the relative orientations of the magnetization of the magnetic layers.
Implementation Method 2
Magnetic flux from the surface of the disc causes rotation of the magnetization vector of a sensing layer or layers of the sensor, which in turn causes a change in the electrical properties of the sensor.
Implementation Method 3
An MR sensor may include shields consisting of high permeability materials that function to protect the sensor from stray magnetic fields originating from adjacent magnetic bits on the medium.
Data Source
AI summary
A magnetic sensor assembly includes first and second shields each comprised of a magnetic material. The first and second shields define a physical shield-to-shield spacing. A sensor stack is disposed between the first and second shields and includes a seed layer adjacent the first shield, a cap layer adjacent the second shield, and a magnetic sensor between the seed layer and the cap layer. At least a portion of the seed layer and/or the cap layer comprises a magnetic material to provide an effective shield-to-shield spacing of the magnetic sensor assembly that is less than the physical shield-to-shield spacing.