Magnetoresistive Element Outer Region Segmentation for Pinned Layer Stability

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Solution Overview

Problem

Existing thin-film magnetic heads with GMR or TMR read head elements face challenges in stabilizing the magnetization direction of the pinned layer due to insufficient shape anisotropy and magnetic bias from domain control layers, which hinders the achievement of higher recording density and sensitivity.

Innovation Solution

The introduction of a nonmagnetic intermediate layer and a magnetization fixed function part, stacked only in the outer region of the magnetization free function part, helps stabilize the magnetization of the pinned layer by minimizing the thickness impact on the read gap and reducing magnetic bias interference, allowing for a narrower read gap and improved output characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the pinned layer is extended toward the height direction to decrease thickness and narrow read gap, then the read gap is narrowed for higher density recording, but the magnetization direction of the pinned layer cannot be stably fixed due to insufficient shape anisotropy and magnetic bias from domain control layers

Engineering Contradiction:

Improveread gap thicknessVSAvoidmagnetization direction stability

Core Design Contradiction:

Length of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent divides the pinned layer structure into two distinct regions: an inner region (facing the air bearing surface) that maintains shape anisotropy for magnetization fixation, and an outer region (opposite side) that accommodates domain control layers. This segmentation allows each region to fulfill its specific function without interference, resolving the contradiction between narrowing read gap and stabilizing magnetization direction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different structural characteristics to different regions of the pinned layer. The inner region is designed with sufficient thickness to maintain shape anisotropy and stable magnetization, while the outer region is positioned to minimize magnetic bias from domain control layers. This local differentiation allows the overall structure to achieve both narrow read gap and stable magnetization fixation.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If the space between lower and upper shield layers is narrowed to achieve higher density recording, then recording density is improved, but the magnetization direction of the pinned layer becomes unstable under magnetic bias from nearby domain control layers

Engineering Contradiction:

Improverecording densityVSAvoidmagnetization fixation stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent segments the pinned layer into inner and outer regions, where the inner region maintains stable magnetization through shape anisotropy while the outer region is positioned to reduce magnetic bias from domain control layers. This segmentation enables the structure to achieve narrow read gap for high density recording while maintaining magnetization stability through functional differentiation of regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a nonmagnetic intermediate layer between the pinned layer and domain control layers in the outer region. This intermediary layer acts as a magnetic shield, reducing the magnetic bias from domain control layers and preventing magnetization instability, thereby enabling reliable magnetization fixation even with narrowed read gap.

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 enables more stable magnetization fixing of the pinned layer, leading to enhanced element output characteristics and higher recording density, while maintaining the sensitivity required for advanced hard disk drive applications.

Implementation Method 1

fix a magnetization direction of the pinned layer with the help of shape anisotropy

Methodology Applied

Scientific EffectShape anisotropy: Anisotropy

Implementation Method 2

a thin-film magnetic head with a giant magnetoresistive effect (GMR) read head element

Methodology Applied

Scientific EffectGiant magnetoresistive effect: Magnetoresistance

Implementation Method 3

a thin-film magnetic head with a tunnel magnetoresistive effect (TMR) read head element

Methodology Applied

Scientific EffectTunnel magnetoresistive effect: Magnetoresistance

Data Source

PatentUS8054587B2Magnetoresistive effect element, thin-film magnetic head with magnetoresistive effect read head element, and magnetic disk drive apparatus with thin-film magnetic head

Publication Date: 2011.11.08 TDK CORP

AI summary

An MR element includes a lower shield layer, a magnetization free function part stacked on the lower shield layer, an upper shield layer stacked on the magnetization free function part, a nonmagnetic intermediate layer stacked on a surface, that is opposite to a magnetically sensitive surface, of the magnetization free function part, and a magnetization fixed function part stacked on the nonmagnetic intermediate layer. The nonmagnetic intermediate layer and the magnetization fixed function part are formed only within an outer region of the magnetization free function part, located opposite side to the magnetically sensitive surface.