Scissor Reader Side Shield Decoupling Bias Material Disturbance

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Solution Overview

Problem

Conventional magnetic read heads with scissor sensors experience disturbance from strong interactions between synthetic antiferromagnetic (SAF) structures and bias materials, affecting the stabilization of the bias material.

Innovation Solution

The magnetic head design includes a sensor stack with a bias material aligned perpendicular to the media facing surface, where the SAF structures laterally bookend the sensor stack and a portion of the bias material, while a dielectric material laterally bookends the remaining portion, decoupling the SAF structures from the bias material and minimizing disturbance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If SAF structures laterally bookend the entire bias material, then the side shields minimize the demagnetization energy of the dual free layer, but the strong interaction between SAF structures and bias material disturbs bias material stabilization

Engineering Contradiction:

Improvedemagnetization energy minimizationVSAvoidbias material stabilization

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The bias material is divided into two portions: a first portion laterally bookended by SAF structures and a second portion laterally bookended by dielectric material. This segmentation allows the first portion to benefit from demagnetization energy minimization while the second portion remains isolated from SAF structure interference, thus resolving the contradiction between minimizing demagnetization energy and maintaining bias material stabilization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Dielectric material is introduced as an intermediary to laterally bookend the second portion of the bias material. This intermediary prevents direct interaction between SAF structures and the bias material at that region, eliminating the disturbing stray field while allowing the first portion to maintain beneficial magnetic interaction for demagnetization energy minimization.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If SAF structures extend to the media facing surface to bookend the sensor stack, then the side shields provide magnetic shielding, but the stray field from SAF structures disturbs bias material stabilization

Engineering Contradiction:

Improvemagnetic shielding effectivenessVSAvoidstray field disturbance

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

Different regions of the bias material are assigned different lateral bookending materials: the first portion uses SAF structures for magnetic shielding and demagnetization energy minimization, while the second portion uses dielectric material to eliminate stray field disturbance. This local differentiation allows each region to have optimized properties for its specific function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Dielectric material serves as an intermediary structure that replaces SAF structures in the region adjacent to the second portion of the bias material. This intermediary blocks the propagation of stray fields from SAF structures to the bias material while maintaining the overall magnetic shielding function through the first portion's SAF structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 reduces the disturbance to the bias material, enhancing the stability and performance of the magnetic read head by minimizing the interaction between SAF structures and bias material.

Implementation Method 1

Side shields, such as synthetic antiferromagnetic (SAF) structures, typically laterally bookend the sensor stack and the bias material. The side shields minimize the demagnetization energy of the dual free layer.

Methodology Applied

Scientific EffectSynthetic antiferromagnetic interaction: Magnetism

Implementation Method 2

a second portion of the bias material is laterally bookended by a dielectric material. In this configuration, the SAF structures are decoupled from the bias material, which minimizes the disturbance to the bias material.

Methodology Applied

Scientific EffectElectromagnetic isolation: Dielectric

Data Source

PatentUS9230576B1Scissor reader with side shield decoupled from bias material

Publication Date: 2016.01.05 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

Embodiments disclosed herein generally relate to a magnetic head having a sensor stack and a bias material that is aligned in a direction perpendicular to a media facing surface. The sensor stack and a first portion of the bias material are laterally bookended by synthetic antiferromagnetic (SAF) structures, and a second portion of the bias material is laterally bookended by a dielectric material. In this configuration, the SAF structures are decoupled from the bias material, which minimizes the disturbance to the bias material.