HAMR Write Head Gap Current Layout to Reduce Adjacent Track Interference
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Solution Overview
Problem
Current hard-disk-drive (HDD) write heads face challenges in achieving optimal current-assisted areal density capacity (ADC) gain due to uneven current distribution and adjacent track interference (ATI) in heat-assisted magnetic recording (HAMR) technologies, which degrade writability as dimensions scale down.
Innovation Solution
A magnetic write head structure with optimized gap current distribution, incorporating a non-dual-write-shield (nDWS) design that includes a main pole, trailing shield, side shield, and write gap, with specific current paths through side and leading gaps, and optional insulators to balance current flow and minimize ATI, using materials like NiCr and NiCr/Ru alloys to adjust path resistances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If current is provided through the write gap to achieve current-assisted ADC gain, then ADC gain is improved, but adjacent track interference increases
Solution Approach 1:
The patent applies local quality by providing different current paths with different resistance characteristics to different regions. The write gap is designed with specific resistance properties compared to side gap paths, allowing localized current distribution that optimizes ADC gain in the write gap while controlling interference in adjacent tracks through resistance-based current steering.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the resistance values of different gap paths (write gap, side gaps) through material selection and geometric design. By changing the resistance parameters of these paths, the current distribution is optimized to achieve maximum ADC gain while minimizing adjacent track interference through controlled current flow.
2Productivity
If write head dimensions are scaled down to increase recording density, then areal density capacity is improved, but writability degrades
Solution Approach 1:
The patent employs the copying principle by creating multiple current paths (write gap path, side gap paths) that replicate and distribute the current flow. This allows the magnetic field generation to be copied across multiple routes, maintaining sufficient write field strength even as the overall write head dimensions are scaled down to increase recording density.
Solution Approach 2:
The patent applies segmentation by dividing the current path into multiple separate routes through different gaps (write gap, side gaps). This segmentation allows current to be distributed across multiple paths, maintaining adequate magnetic field strength at the write tip even when the overall device dimensions are reduced for higher areal density capacity.
3Productivity
If current distribution is optimized through resistance control, then ADC gain is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by allowing the current distribution to be automatically controlled through the inherent resistance characteristics of different gap paths. The write head structure itself, through its geometric and material design, passively steers current flow without requiring external control mechanisms, thus achieving optimized ADC gain while minimizing device complexity.
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 optimized current distribution enhances writability and ADC gain by up to ˜2.7 times, reducing ATI and maintaining reliability, thus addressing the limitations of existing HAMR and MAMR technologies.
Implementation Method 1
a coil wrapped around the MP through a PP3 shield that is configured to direct a time-dependent write current to saturate magnetization of the MP
Implementation Method 2
a current is configured to be provided through the MP to one of a side of the WS or SS to induce a current-assisted ADC gain
Implementation Method 3
HAMR can include heating a small region of the magnetic medium to near its Curie temperature where its coercivity and anisotropy are significantly reduced
Data Source
AI summary
The present embodiments can generally provide a magnetic write head structure with optimized gap current distribution to maximize the current-assisted areal density capacity (ADC) gain in hard-disk-drive storage devices. In a first example embodiment, a non-dual-write-shield (nDWS) write head can include a main pole (MP), a trailing shield (TS), and a write gap (WG) disposed between the MP and the TS. The write head can also include a side shield (SS), a leading shield (LS), and a write shield (WS). The write head can include a side gap (SG) between the MP and the SS on both sides of the MP tip, and a leading gap (LG) between the MP and the LS. The write head can also include a coil wrapped around the MP through a PP3 shield that is configured to direct a time-dependent write current to saturate magnetization of the MP.