NiFeX Magnetic Shield Annealing Stability
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Solution Overview
Problem
Magnetic transducers face challenges in high-temperature annealing processes, where traditional NiFe shields deteriorate due to grain coarsening and loss of anisotropy, limiting the ability to process materials effectively at temperatures above 350°C.
Innovation Solution
Incorporating NiFeX materials, where X is Nb, Mo, or W, into the shields, allowing for annealing at temperatures of at least 350°C without detrimental effects, and using alternating bilayers of NiFeX and NiFe to maintain magnetic properties and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional NiFe shields are used in magnetic transducers, then the shields can be fabricated using conventional processes, but the shields deteriorate when subjected to annealing temperatures above 350°C due to grain coarsening and loss of anisotropy
Solution Approach 1:
The patent modifies the chemical composition parameters of the shield material by incorporating refractory metals (Nb, Mo, Ta, or W) at concentrations of 0.1-10 atomic percent into the NiFe alloy. This compositional parameter change enables the shield to withstand annealing temperatures above 350°C while maintaining magnetic properties, directly resolving the contradiction between temperature resistance and magnetic property stability.
Solution Approach 2:
The patent creates a composite shield material by combining NiFe with refractory metal elements (Nb, Mo, Ta, or W). This composite structure leverages the high thermal stability of refractory metals while retaining the soft magnetic properties of NiFe, enabling the shield to maintain both mechanical integrity and magnetic performance at elevated annealing temperatures above 350°C.
2Ease of manufacture
If shields are annealed at higher temperatures to match reader stack processing requirements, then advanced reader stack materials can be processed effectively, but traditional NiFe shields suffer grain coarsening and degradation
Solution Approach 1:
The patent changes the compositional parameters of the shield material by adding refractory metals (Nb, Mo, Ta, or W) at 0.1-10 atomic percent concentrations. This compositional modification allows the shield to undergo high-temperature annealing (above 350°C) required for advanced reader stack materials without suffering grain coarsening, thus achieving both processing compatibility and microstructure control.
Solution Approach 2:
The patent uses small concentrations (0.1-10 at%) of expensive refractory metal elements as additives in the NiFe shield. These small amounts of high-value materials provide substantial thermal stability improvement, allowing the shield to survive high-temperature processing that would otherwise destroy conventional shields, effectively making the shield 'disposable' resistant to thermal degradation.
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 use of NiFeX shields enables high-temperature annealing without grain growth or degradation, maintaining magnetic moment and coercivity, thus enhancing the thermal stability and performance of magnetoresistive sensors in magnetic transducers.
Implementation Method 1
annealing the precursor device at a temperature of at least about 350° C.
Implementation Method 2
maintaining magnetic moment and coercivity, thus enhancing the thermal stability and performance
Data Source
AI summary
A device including a magnetoresistive sensor; a top shield; and a bottom shield, wherein the magnetoresistive sensor is positioned between the top shield and the bottom shield, and wherein at least one of the bottom shield and the top shield include NiFeX, wherein X is chosen from Nb, Mo, Ta, or W.