Composite Top Shield for MR Sensor Stabilization
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Solution Overview
Problem
Magnetic data storage systems face challenges in achieving high data densities and stabilizing magnetoresistive (MR) sensors as they shrink, leading to increased variation in magnetization direction and reduced signal-to-noise ratio due to reduced shield-to-shield spacing.
Innovation Solution
The implementation of a composite top shield with a synthetic antiferromagnetic (SAF) portion and a bulk shield portion, featuring multiple layers with high magnetic moment and corrosion-resistant materials, improves shield stabilization and reduces stray magnetic field interference, enhancing the spatial resolution and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sensor size is reduced to achieve high data densities, then data storage capacity increases, but magnetization direction variation increases and signal-to-noise ratio decreases
Solution Approach 1:
The top shield is segmented into multiple functional layers including soft magnetic material layers and high magnetic moment material layers (≥1.4 T), with alternating soft and hard magnetic layers creating distinct functional zones for field shaping and stabilization
Solution Approach 2:
The shield uses composite magnetic structures combining soft magnetic materials (for field shaping) with hard magnetic materials having high magnetic moment (≥1.4 T) (for stabilization), creating a multi-layer composite structure that provides both flexibility and stability
2Quantity of substance
If shield-to-shield spacing is reduced to increase data density, then storage capacity increases, but stray magnetic field interference increases
Solution Approach 1:
The high magnetic moment material layers (≥1.4 T) convert potential stray field interference into beneficial field confinement, using the same magnetic interactions that could cause harm to instead stabilize and contain the magnetic fields within desired regions
Solution Approach 2:
The invention changes the magnetic moment parameter of specific shield layers to at least 1.4 T, fundamentally altering the magnetic field interaction characteristics to provide better field confinement and reduced interference at reduced spacing
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
The composite shield structure provides improved magnetic anisotropy and high magnetic moment, stabilizing the sensor and reducing pulse width, thereby enhancing data storage system performance by increasing signal-to-noise ratio and data density.
Implementation Method 1
The SAF portion comprises a top magnetic layered structure and a bottom magnetic layered structure with a non-magnetic layer therebetween
Implementation Method 2
The composite shield structure provides improved magnetic anisotropy and high magnetic moment
Implementation Method 3
At least one of the magnetic layered structures has a soft magnetic material layer bounded by layers having a magnetic moment of at least 1.4 T
Implementation Method 4
Magnetic flux from the surface of the disc causes rotation of the magnetization vector of a sensing layer of the MR sensor, which in turn causes a change in electrical resistivity of the MR sensor
Data Source
AI summary
A reader sensor comprising a sensor stack and a composite top shield. The composite top shield includes a bulk shield portion and a SAF portion, the SAF portion comprising a top magnetic layered structure and a bottom magnetic layered structure with a non-magnetic layer therebetween. Each of the magnetic layered structures has at least one soft magnetic material layer bounded by layers comprising magnetic material having a magnetic moment of at least 1.4 T.