Heusler Alloy Regularization via Silver Diffusion

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The use of Heusler alloy in magnetic field detecting elements for CPP-GMR heads requires high temperature annealing for regularization, which is close to the upper limit for maintaining the nature of shield layers, preventing sufficient regularization and limiting the exploitation of Heusler alloy's potential.

Innovation Solution

Incorporating a silver-type metal layer, such as silver, gold, copper, or platinum, adjacent to the Heusler alloy layer, which diffuses and migrates during heating, mitigates stress and reduces the regularization temperature by forming a solid solution in the metal layer, allowing for lower temperature annealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high temperature annealing is applied to regularize Heusler alloy, then the regularization of crystal structure is improved, but the shielding characteristics of shield layers deteriorate

Engineering Contradiction:

Improveregularization of crystal structureVSAvoidshielding characteristics

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

A metal layer (silver, gold, copper, palladium, or platinum) is introduced as an intermediary between the Heusler alloy layer and the spacer adjoining layer. This metal layer acts as a mediator that facilitates stress relief and regularization at lower temperatures, preventing direct high-temperature exposure that would harm the shield layers while still achieving the desired crystal structure regularization in the Heusler alloy.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the temperature parameter of the annealing process by introducing the metal layer, which enables regularization to occur at lower temperatures (below the upper limit for shield layer maintenance) through stress mitigation and solid solution formation, thus decoupling the temperature requirements for Heusler alloy regularization from shield layer protection constraints.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If Heusler alloy is used to increase spin polarizability, then the magneto-resistance ratio is improved, but the regularization temperature becomes too high for practical application

Engineering Contradiction:

Improvemagneto-resistance ratioVSAvoidregularization temperature

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The metal layer serves as an intermediary that enables stress relief and regularization at lower temperatures. By forming a solid solution with the Heusler alloy and migrating during heating, it facilitates crystal structure regularization without requiring temperatures that would compromise shield layer characteristics, thus making high spin polarizability materials practically applicable.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite structure consisting of the Heusler alloy layer combined with a metal layer (silver, gold, copper, palladium, or platinum). This composite material system leverages the high spin polarizability of the Heusler alloy while the metal component provides stress mitigation and enables lower temperature processing, achieving both high magneto-resistance ratio and practical manufacturing temperature.

Inventive Principle:

Principle #40Composite materials

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 effectively reduces the regularization temperature of the Heusler alloy, promoting its regularization and maintaining the shielding characteristics of the shield layers, thereby enhancing the magnetic field detecting element's performance.

Implementation Method 1

Incorporating a silver-type metal layer, such as silver, gold, copper, or platinum, adjacent to the Heusler alloy layer, which diffuses and migrates during heating

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

which diffuses and migrates during heating, mitigates stress and reduces the regularization temperature by forming a solid solution in the metal layer

Methodology Applied

Scientific EffectMigration: Diffusion

Implementation Method 3

reduces the regularization temperature by forming a solid solution in the metal layer

Methodology Applied

Scientific EffectSolid solution formation: Solid Solution Strengthening

Data Source

PatentUS7895731B2Method for manufacturing magnetic field detecting element utilizing diffusion and migration of silver

Publication Date: 2011.03.01 TDK CORP

AI summary

A method for manufacturing a magnetic field detecting element having a free layer whose magnetization direction is variable depending on an external magnetic field and a pinned layer whose magnetization direction is fixed and these are stacked with an electrically conductive, nonmagnetic spacer layer sandwiched therebetween, wherein sense current flows in a direction perpendicular to film planes of the magnetic field detecting element. The method comprises: forming a spacer adjoining layer adjacent to the spacer layer, Heusler alloy layer, and a metal layer successively in this order; and forming either at least a part of the pinned layer or the free layer by heating the spacer adjoining layer, the Heusler alloy layer, and the metal layer. The spacer adjoining layer has a layer chiefly made of cobalt and iron. The Heusler alloy layer includes metal which is silver, gold, copper, palladium, or platinum, or an alloy thereof. The metal layer is made of the same.