CPP GMR Device Tapered Outer Pin Layer for Narrow Inter-Shield Gap
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Solution Overview
Problem
Existing GMR devices with a CPP structure face challenges in achieving higher recording densities due to the thickness of the outer pin layer, which affects the inter-shield gap and resistance change, while maintaining the stability of the synthetic pinned layer.
Innovation Solution
A GMR device with a CPP structure is designed, where the width of the inner pin layer is set at 50 nm or less, and the outer pin layer is tapered with a specific angle range, allowing for a magnetic volume and thickness ratio that balances the magnetic moments, thereby reducing the outer pin layer thickness without compromising the synthetic pinned layer's function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the outer pin layer thickness is reduced to achieve higher recording densities, then the inter-shield gap can be narrowed, but the stability of the synthetic pinned layer may be compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of the outer pin layer to 5 nm or less (a specific quantitative parameter), while adjusting the width of the inner pin layer to 50 nm or less. These parameter changes enable the outer pin layer to be sufficiently thin to narrow the inter-shield gap while maintaining the magnetic volume ratio balance that ensures synthetic pinned layer stability.
Solution Approach 2:
The patent applies local quality by creating different width dimensions for the inner and outer pin layers. The inner pin layer has a width of 50 nm or less while the outer pin layer has a reduced thickness of 5 nm or less. This local differentiation in dimensions allows each layer to fulfill its specific function - the inner layer provides magnetic moment balance while the outer layer enables gap reduction without compromising overall stability.
2Stability of the object's composition
If the inner pin layer width is reduced to 50 nm or less, then the magnetic moment balance is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a concrete parameter threshold of 50 nm for the inner pin layer width, which provides a clear manufacturing target. This quantitative parameter change enables magnetic moment balance while establishing a feasible precision requirement for fabrication processes.
3Stability of the object's composition
If the outer pin layer is tapered with a specific angle, then the magnetic volume ratio is optimized, but the device complexity increases
Solution Approach 1:
The patent applies asymmetry by introducing a tapered structure in the outer pin layer with a specific angle range. This asymmetric geometry optimizes the magnetic volume ratio between the inner and outer pin layers, ensuring proper magnetic moment balance while maintaining a manageable structural complexity through defined geometric parameters.
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 a narrower inter-shield gap, improving recording densities and maintaining resistance to external magnetic fields, while achieving higher output potentials.
Implementation Method 1
GMR devices having the so-called CPP (current perpendicular to plane) structure wherein the sense current is passed perpendicularly to the plane of each of the layers forming the GMR device
Implementation Method 2
a pinning layer (generally an antiferromagnetic layer) on the side of the fixed magnetization layer facing away from the non-magnetic layer. The fixed magnetization layer has its magnetization direction fixed by a magnetic field from the pinning layer
Implementation Method 3
The free layer has its magnetization direction changing depending on an external signal magnetic field
Data Source
AI summary
In the GMR device of the CPP structure using the synthetic pinned layer as the fixed magnetization layer (pinned layer), the width W1 of the inner pin layer is set at 50 nm or less; the fixed magnetization layer is configured in such a way as to have a given angle range of tapers at both its ends as viewed from the medium opposite plane; the magnetic volume ratio between the inner and the outer pin layer is allowed to lie in the range of 0.9 to 1.1; and the magnetic thickness ratio between the inner and the outer pin layer is set at 0.8 or less. It is thus possible to make the outer pin layer thin at no cost of the thickness of the inner pin layer forming a part of the synthetic pinned layer yet without doing damage to the function of the synthetic pinned layer itself, viz., resistance to an external magnetic field.