Gradient Composition Free Magnetic Layer for Waveform Symmetry
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Solution Overview
Problem
Magnetic sensing elements with pinned and free magnetic layers experience increased asymmetry in reproduction waveforms due to enhanced ferromagnetic coupling magnetic fields caused by surface waves, leading to reduced detection sensitivity and output stability when exposed to external magnetic fields.
Innovation Solution
The magnetic sensing element is configured with a free magnetic layer and a pinned magnetic layer, where the atomic percentage of element Z in the metal compound is decreased near the non-magnetic material layer interface and increased further away, using specific compositional formulas to reduce ferromagnetic coupling and maintain high spin-dependent bulk scattering coefficients, thereby stabilizing the reproduction output and reducing waveform asymmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the free magnetic layer and pinned magnetic layer are formed with uniform composition, then the manufacturing process is simple, but surface waves are generated leading to enhanced ferromagnetic coupling magnetic fields and increased reproduction waveform asymmetry
Solution Approach 1:
The patent applies local quality by creating a compositional gradient in the free magnetic layer where the concentration of element Z varies through the film thickness. Specifically, the atomic percentage of element Z is higher near the non-magnetic material layer interface and decreases toward the opposite surface. This local compositional variation reduces the ferromagnetic coupling magnetic field between the free and pinned magnetic layers, thereby reducing reproduction waveform asymmetry while maintaining a manufacturable gradient structure through controlled deposition processes.
2Measurement precision
If the atomic percentage of element Z is increased throughout the free magnetic layer, then the spin-dependent bulk scattering coefficient is enhanced, but the ferromagnetic coupling magnetic field is strengthened leading to increased reproduction waveform asymmetry
Solution Approach 1:
The patent resolves this contradiction by applying local quality through a spatially varying composition. The free magnetic layer contains element Z with a gradient distribution: higher concentration near the non-magnetic material layer interface to reduce ferromagnetic coupling and waveform asymmetry, and lower concentration toward the opposite surface to maintain appropriate spin-dependent bulk scattering. This localized compositional control allows simultaneous optimization of both detection sensitivity and waveform symmetry.
Solution Approach 2:
The patent employs parameter changes by varying the atomic percentage of element Z as a continuous parameter through the film thickness. Rather than maintaining a uniform composition or using discrete layers, the concentration of element Z is gradually adjusted from higher values near the non-magnetic material interface to lower values at the opposite surface. This continuous parameter variation enables fine-tuned control over both the ferromagnetic coupling field and spin-dependent scattering properties.
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 enhances the detection sensitivity and output stability by reducing ferromagnetic coupling magnetic fields, maintaining a high product of magnetic resistance change and element area, and achieving compatible high reproduction output and reduced asymmetry in waveforms.
Implementation Method 1
the ferromagnetic coupling magnetic field Hin due to the magnetostatic coupling (topological coupling) between the pinned magnetic layer 4 and the free magnetic layer 6 is enhanced
Implementation Method 2
An exchange coupling magnetic field is generated at the interface between the antiferromagnetic layer 3 and the pinned magnetic layer 4 and, thereby, the magnetization of the above-described pinned magnetic layer 4 is pinned in a height direction
Implementation Method 3
maintaining a high product of magnetic resistance change and element area
Data Source
AI summary
A magnetic sensing element which allows a high reproduction output and reduction in asymmetry of reproduction waveform to become mutually compatible, as well as a method for manufacturing the same, is provided. In the inside of a second pinned magnetic layer and a free magnetic layer, the atomic percentage of an element Z is decreased in a region close to a non-magnetic material layer. Consequently, the ferromagnetic coupling magnetic field due to magnetostatic coupling (topological coupling) between the pinned magnetic layer and the free magnetic layer can be reduced. At the same time, in a region at a distance from the non-magnetic material layer, the atomic percentage of an element Z is increased, a spin-dependent bulk scattering coefficient is increased, and a product of the amount of change in magnetic resistance and the element area of the magnetic sensing element can be maintained at a high level.