High Moment Bilayer Seed Layer for Trailing Shield Saturation
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Solution Overview
Problem
Conventional magnetic recording transducers face issues at higher densities due to saturation of the trailing shield, leading to inadequate shielding and a lower magnetic field gradient, resulting in errors in disk drives.
Innovation Solution
A magnetic recording transducer design featuring a write pole, nonmagnetic gap, high moment layer, and magnetic buffer layer, where the high moment layer has a saturation magnetization greater than 2.3 T and a corrosion potential, and the magnetic buffer layer has a lower corrosion potential, is used to improve the trailing shield's performance and resistance to corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the trailing shield is scaled to smaller dimensions to achieve higher recording densities, then the throat height can be reduced to 60-80 nm or less, but the trailing shield may saturate during operation and be unable to adequately shield the pole from the media
Solution Approach 1:
The patent applies composite materials by creating a multi-layer magnetic seed layer structure consisting of a high moment layer (CoFeB with Ms>2.3T) combined with a magnetic buffer layer (CoFe or CoFeB). This composite structure provides both the high saturation magnetization needed to prevent trailing shield saturation and the corrosion resistance required for reliable operation at high recording densities
Solution Approach 2:
The patent changes material parameters by selecting specific compositions for the magnetic seed layer: the high moment layer uses CoFeB alloy with saturation magnetization greater than 2.3 T, while the magnetic buffer layer uses CoFe or CoFeB with appropriate thickness (5-20 nm). These parameter changes enable the trailing shield to maintain adequate shielding capability at reduced throat heights of 60-80 nm or less
2Productivity
If the track width of the pole is decreased to achieve higher densities, then the throat height must be reduced, but the gradient in the magnetic field from the write pole may be lower than desired
Solution Approach 1:
The composite magnetic seed layer structure with high moment layer (CoFeB, Ms>2.3T) and magnetic buffer layer enables maintaining strong magnetic field gradients by preventing saturation of the trailing shield, even when track width and throat height are reduced for higher recording densities
3Device complexity
If a conventional magnetic seed layer is used, then the structure is simple, but the trailing shield may be subject to corrosion and degradation at high densities
Solution Approach 1:
The patent uses composite materials to create a two-layer magnetic seed layer structure where the magnetic buffer layer (CoFe or CoFeB, 5-20 nm thick) provides corrosion resistance while the high moment layer (CoFeB, Ms>2.3T) provides the necessary magnetic properties. This composite approach improves reliability against corrosion and degradation at high densities while maintaining acceptable structural complexity
Solution Approach 2:
The magnetic buffer layer acts as an intermediary between the high moment layer and the trailing shield, providing corrosion protection to the high moment layer while allowing the magnetic field to pass through effectively. This intermediary layer prevents direct exposure of the high moment layer to corrosive environments
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 design enhances the saturation properties and corrosion resistance of the trailing shield, maintaining a strong magnetic field gradient and improving the reliability and performance of the transducer at higher densities.
Implementation Method 1
The high moment layer has a saturation magnetization greater than 2.3 T
Implementation Method 2
The magnetic buffer layer has a second corrosion potential less than the first corrosion potential
Data Source
AI summary
A method and system for providing a magnetic read transducer is described. The magnetic recording transducer includes a write pole, a nonmagnetic gap, a magnetic seed layer, a trailing shield and coil(s) that energize the write pole. The write pole is configured to write to a media. The nonmagnetic gap is between the write pole and the magnetic seed layer. The magnetic seed layer includes a high moment layer and a magnetic buffer layer. The high moment layer is between the nonmagnetic gap and the magnetic buffer layer. The high moment layer has a saturation magnetization greater than 2.3 T and a first corrosion potential. The magnetic buffer layer has a second corrosion potential less than the first corrosion potential. The magnetic seed layer is between the trailing shield and the nonmagnetic gap layer. The magnetic buffer layer is between the trailing shield and the high moment layer.