PP3 Trailing Shield Shape Anisotropy for PMR STE Control
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Solution Overview
Problem
Perpendicular magnetic recording (PMR) writers face challenges in achieving high area density capability (ADC) and reducing skip track erasure (STE) due to unpredictable magnetic flux return pathways, leading to bit error rate (BER) and noise issues, especially as data rate demands increase for cloud storage and high-end disk drives.
Innovation Solution
The design of a PMR shield with a modified trailing shield shape, such as a tree top shape, is introduced to generate shape anisotropy, ensuring consistent magnetization orientation during hard magnetic initialization (HMI) and reverse magnetic initialization (RMI), thereby improving both area density capability and skip track erasure robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional rectangular PP3 trailing shield is used, then manufacturing is simple, but magnetization orientation is unpredictable leading to poor STE robustness
Solution Approach 1:
The PP3 trailing shield transitions from a symmetric rectangular shape to an asymmetric shape with a sloped section. This asymmetry creates shape anisotropy that provides a preferred magnetization direction, forcing consistent magnetization orientation across devices and improving STE robustness by eliminating the bimodal distribution of magnetization states.
Solution Approach 2:
The sloped section is introduced at a specific location on the PP3 trailing shield to create localized shape anisotropy. This local geometric modification generates a preferred magnetization direction in the trailing shield, which then influences the magnetization orientation of adjacent shields through magnetic coupling, improving overall STE performance.
2Reliability
If the PP3 trailing shield shape is modified to improve magnetization control, then STE robustness improves, but area density capability may be slightly reduced
Solution Approach 1:
The shield shape is modified by changing geometric parameters (introducing a sloped section with specific angles and dimensions) to create shape anisotropy. This parameter change provides magnetization control and improves STE robustness while the design is optimized to minimize the impact on area density capability.
3Reliability
If additional sides are introduced to the PP3 shield, then shape anisotropy is generated for better magnetization control, but device complexity increases
Solution Approach 1:
Rather than adding multiple sides to create complex geometry, the invention introduces a single sloped section that breaks the symmetry of the rectangular shield. This creates sufficient shape anisotropy to establish preferred magnetization directions without significantly increasing geometric complexity or manufacturing difficulty.
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 modified trailing shield shape ensures nearly 100% of PMR writer devices exhibit improved magnetization control, enhancing area density capability and maintaining or improving skip track erasure performance with a slight trade-off in area density, thus addressing the BER and noise issues in PMR writers.
Implementation Method 1
By introducing additional sides between the PP3 trailing shield front side and backside, shape anisotropy is generated such that PP3 magnetization is substantially in a single cross-track direction
Implementation Method 2
a method of magnetic initialization including hard magnetic initialization (HMI) and reverse magnetic initialization (RMI)
Data Source
AI summary
A shield structure for a PMR writer is disclosed and features a first trailing shield on a write gap, and a second (PP3) trailing shield on the first trailing shield and magnetically connected to the main pole layer. From a top-down view along the down-track direction, the PP3 trailing shield has various shapes to provide shape anisotropy such that following hard magnet or reverse magnet initialization, PP3 trailing shield magnetic orientation has a stable three domain configuration thereby minimizing skip track erasure (STE) or improving area density capability (ADC). At least one sloped side is introduced that forms an angle >90 degrees with the PP3 trailing shield backside. In other embodiments, a thinner leading shield may be used to improve STE. The PP3 trailing shield may have a dome shape or a planar shape from a down-track cross-sectional view.