Magnetic Write Pole Tapered Trailing End with Negative Anisotropy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Perpendicular magnetic recording (PMR) write heads face issues with flux shunting into the write gap and side gaps, leading to reduced bit density and overwrite performance due to the need for narrow write and side gaps, which increases the likelihood of unwanted flux paths.
Innovation Solution
The write pole incorporates a main portion of conventional high-moment magnetic materials with a beveled or tapered trailing portion made of Co/Fe multilayer having negative magnetic anisotropy, which directs flux perpendicularly to the recording layer and prevents flux leakage into the write gap and side gaps, enhancing bit and track density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the write gap and side gaps are made narrow to achieve high BPI and TPI, then the bit density and track density improve, but flux shunting into the gaps increases reducing writability
Solution Approach 1:
The write pole is designed with different magnetic properties at different locations: the main body uses conventional high-moment magnetic materials while the trailing end section uses Co/Fe multilayer with negative magnetic anisotropy. This local differentiation allows the trailing end to specifically prevent flux shunting into the write gap while the main body provides the necessary magnetic moment for writing, thus resolving the contradiction between narrow gap requirements and flux leakage prevention.
Solution Approach 2:
The write pole employs a composite structure combining conventional high-moment magnetic materials with Co/Fe multilayer materials having negative magnetic anisotropy. This composite design leverages the high saturation magnetization of conventional materials for writing capability while utilizing the unique magnetic anisotropy properties of Co/Fe multilayer to direct flux perpendicularly and prevent shunting into narrow gaps, thereby achieving both high bit density and maintained writability.
2Quantity of substance
If the write gap is made narrow to achieve high BPI, then the bit density improves, but flux leakage into the write gap increases reducing the flux to the recording layer
Solution Approach 1:
The trailing end section of the write pole is specifically engineered with Co/Fe multilayer materials having negative magnetic anisotropy, creating a localized region with unique magnetic properties. This local modification ensures that flux is directed perpendicularly through the narrow write gap to the recording layer rather than leaking sideways, thus achieving high bit density while minimizing flux loss.
Solution Approach 2:
The invention changes the magnetic anisotropy parameter of the write pole material at the trailing end from conventional positive anisotropy to negative magnetic anisotropy using Co/Fe multilayer. This parameter change fundamentally alters the flux distribution pattern, forcing flux to pass through the narrow write gap perpendicular to the disk surface rather than shunting along the gap edges, thereby reducing flux leakage while maintaining high bit density capability.
3Quantity of substance
If the side gaps are made narrow to achieve high TPI, then the track density improves, but flux shunting into side gaps increases resulting in loss of overwrite performance
Solution Approach 1:
The write pole incorporates Co/Fe multilayer with negative magnetic anisotropy at the trailing end section, creating a localized magnetic field configuration that confines flux strictly within the intended write path. This local magnetic property differentiation prevents flux from shunting into the narrow side gaps, thereby achieving high track density while preserving overwrite performance by maintaining proper flux confinement.
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 results in a 3% improvement in bit density and a 2 dB gain in overwrite performance by effectively directing flux and preventing leakage, thereby improving the writability and recording capabilities of the PMR write head.
Implementation Method 1
a beveled or tapered trailing portion formed of a Co/Fe multilayer with negative magnetic anisotropy (negative anisotropy constant or -Ku)
Implementation Method 2
The Co/Fe multilayer tapered trailing portion has a high saturation magnetization (Ms) and thus functions as part of the write pole to direct the flux perpendicularly to the recording layer
Implementation Method 3
the -Ku Co/Fe multilayer tapered trailing portion has its hard axis oriented substantially orthogonal to the layer thickness and thus substantially prevents flux leakage into the write gap
Data Source
AI summary
A perpendicular magnetic recording write head includes a main portion formed of conventional high-moment magnetic materials, and a beveled or tapered trailing portion formed of a Co/Fe multilayer with negative magnetic anisotropy (negative anisotropy constant or —Ku). The Co/Fe multilayer tapered trailing portion has a high saturation magnetization (Ms) and thus functions as part of the write pole to direct the flux perpendicularly to the recording layer. Also, the —Ku Co/Fe multilayer tapered trailing portion has its hard axis oriented substantially orthogonal to the layer thickness and thus substantially prevents flux leakage into the write gap. The —Ku Co/Fe multilayer may also be formed on the sides of the write pole in the cross-track direction to prevent flux leakage into the side gaps.