Composite Main Pole for Magnetic Writer Flux Leakage
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Solution Overview
Problem
Conventional perpendicular magnetic recording (PMR) writers have limitations in achieving high data rates due to excessive writer flux leakage, which affects the Wide Area Track Erasure (WATER) performance and reliability, particularly in maintaining sufficient write field and field gradient at the air-bearing surface (ABS).
Innovation Solution
A PMR writer design with a main pole composed of composite magnetic materials, featuring distinct magnetic properties in different portions, is introduced. The main pole includes a first portion with higher magnetic moment and stress at the ABS vicinity for enhanced write field and field gradient, and a second portion with lower magnetic properties spaced apart from the ABS to mitigate flux leakage, thereby improving WATER performance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PMR writers with uniform main pole materials are used, then the structure is simple and manufacturing is easier, but writer flux leakage occurs excessively which degrades WATER performance and reliability
Solution Approach 1:
The main pole is segmented into multiple portions (first portion and second portion) with different magnetic materials or properties. The first portion has higher magnetic moment and stress for enhanced write field at the ABS vicinity, while the second portion has lower magnetic properties to mitigate flux leakage. This segmentation allows optimization of different regions for different functions, resolving the contradiction between reliability and complexity.
Solution Approach 2:
Different portions of the main pole are assigned different local magnetic properties. The first portion near the ABS has higher magnetic moment and stress to provide sufficient write field and field gradient, while the second portion spaced from the ABS has lower magnetic properties to reduce flux leakage. This local differentiation improves WATER performance without requiring complete structural redesign.
2Reliability
If the main pole is designed with higher magnetic moment and stress throughout, then write field and field gradient at ABS are enhanced, but flux leakage increases which degrades WATER performance
Solution Approach 1:
The patent applies local quality by creating spatial variation in magnetic properties within the main pole. The first portion has higher magnetic moment and stress concentrated near the ABS to enhance write field and field gradient where needed, while the second portion has lower magnetic properties in regions where flux leakage occurs. This localized optimization achieves both enhanced write capability and reduced flux leakage simultaneously.
Solution Approach 2:
The patent converts the harmful effect of flux leakage by strategically placing lower magnetic property materials in the second portion of the main pole. This design allows the higher magnetic moment portions to generate strong write fields while the lower magnetic moment portions act as flux containment regions, converting what would be leakage into controlled magnetic flux paths that improve WATER performance.
3Reliability
If composite magnetic materials are used in the main pole, then WATER performance and reliability are improved, but manufacturing complexity increases
Solution Approach 1:
The main pole is fabricated as a composite structure with segmented magnetic materials. The first portion and second portion can be formed using sequential deposition processes or by patterning different materials in different regions. This segmentation enables precise control over magnetic properties in each region while using established thin-film fabrication techniques, making the composite structure manufacturable.
Solution Approach 2:
The patent employs composite magnetic materials in the main pole, combining materials with different magnetic moments and stress properties. This composite approach allows optimization of WATER reliability margin by selecting materials with complementary properties, while the materials themselves are compatible with standard magnetic recording head fabrication processes.
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 proposed PMR writer design achieves higher magnetic moment and stress at the writer pole tip, reducing distortions and enhancing the Wide Area Track Erasure reliability margin by effectively managing writer flux leakage, thus enabling higher data rates beyond 2500 megabits per second.
Implementation Method 1
the write head includes a write pole for directing a magnetic field to the recording layer of a magnetic recording medium or stack
Implementation Method 2
the first portion has a different magnetic property than that of the second portion... the first portion has higher magnetic moment and stress at the ABS vicinity for enhanced write field and field gradient
Implementation Method 3
In a PMR reader, a magnetoresistive (MR) sensor or transducer is frequently employed in the read head
Data Source
AI summary
A magnetic transducer with a composite main pole and methods for fabricating the magnetic transducer are provided. The magnetic transducer includes a main pole having at least a first portion and a second portion. The first portion includes a first magnetic material and has a first side forming at least a portion of an air bearing surface (ABS) of the main pole. The second portion includes a second magnetic material that is different from the first magnetic material, and the second portion is spaced apart from the ABS. The main pole may further include a third portion, where the second portion and the third portion are each located at one of the trailing side or the leading side of the main pole, with the third portion made of magnetic material that is different from the first magnetic material, and the third portion being spaced apart from the ABS.