Multi-level tapered write pole for PMR heads
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Solution Overview
Problem
Perpendicular magnetic recording heads face challenges in achieving high recording area densities due to destabilizing thermal effects and the need for stronger magnetic interactions, which are not adequately addressed by traditional longitudinal recording heads.
Innovation Solution
A multi-level tapered write pole structure is introduced, with the first taper at the pole tip and a second taper at the edges of the yoke structures, enhancing magnetic flux delivery to the air bearing surface (ABS) and improving field gradient and writing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional longitudinal magnetic recording head is used, then the device complexity is low, but the recording area density is insufficient due to superparamagnetic limit
Solution Approach 1:
The write pole is divided into multiple segments with different taper angles along its length. The pole tip has a first taper angle, while the upper portion has a second taper angle, creating a multi-level tapered structure that optimizes flux delivery at different positions
Solution Approach 2:
Different portions of the write pole are given different geometric properties (taper angles) to optimize local flux delivery. The pole tip region has a specific taper angle optimized for flux concentration, while the upper portion has a different taper angle for flux generation
2Manufacturing precision
If the pole tip footprint is reduced to increase recording density, then the domain size decreases, but the magnetic field strength becomes insufficient
Solution Approach 1:
The write pole extends in the vertical dimension (away from the air bearing surface) with a multi-level tapered structure. This vertical extension allows the pole to deliver strong magnetic flux to a reduced footprint area at the air bearing surface, effectively adding a dimension to the flux delivery path
3Productivity
If a single-level tapered pole is used, then the flux delivery is improved, but the field gradient and writing capability are not optimized
Solution Approach 1:
The write pole is segmented into at least two distinct regions along its length, each with a different taper angle. The pole tip region has a first taper angle optimized for flux concentration, while the upper portion has a second taper angle optimized for flux generation, creating a multi-level tapered structure
4Manufacturing precision
If cross-track flux is not controlled, then the writing capability is simplified, but adjacent tracks are affected causing writing errors
Solution Approach 1:
The multi-level tapered pole structure creates localized flux concentration at the pole tip, which inherently confines the magnetic field to the intended track area. The varying taper angles optimize the flux distribution pattern to reduce cross-track flux spread
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 multi-level tapered pole structure significantly increases the magnetic field strength by approximately 4%, enabling higher recording area densities and improved writing performance, including reduced cross-track flux and enhanced stability of domain structures.
Implementation Method 1
A multi-level tapered write pole structure is introduced, with the first taper at the pole tip and a second taper at the edges of the yoke structures, enhancing magnetic flux delivery to the air bearing surface (ABS)
Implementation Method 2
a soft magnetic underlayer (SUL) formed beneath the magnetic layer acts as a stabilizing influence on these perpendicular domain structures and also serves to channel a return flux back to the head to strengthen the recording field
Data Source
AI summary
A method of fabricating a perpendicular magnetic recording (PMR) head with a multi-level tapered write pole which creates an efficient channeling of magnetic flux to the pole tip. A tapered bottom yoke is first formed in an etched substrate and a write pole is formed on the tapered bottom yoke. The write pole comprises a main pole with a tapered tip. A tapered top yoke is then formed on the write pole and symmetrically positioned relative to the bottom yoke. The edge of each yoke is recessed from the ABS of the tapered tip, giving the write pole a stepped profile. The tapered tip can be two sloped surfaces that are symmetric about a mid-plane of the main pole or a single sloped edge on the leading side or the trailing side of the pole.