Adaptive Side Gap Writer for TAMR and MAMR Writability

Solution Overview

Problem

Current Hard Disk Drive (HDD) writer heads face challenges in achieving higher areal density capabilities, particularly in writability under high frequency writing, due to the fixed gap width between the main pole and surrounding shields, which affects bit pattern sharpness and flux release.

Innovation Solution

A new gap structure design is introduced, where thin layers of non-magnetic and magnetic materials are sequentially deposited on the side and leading shields, allowing the gap to adapt to varying writing frequencies by altering permeability, enhancing writability and flux release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If smaller gap width is used between main pole and surrounding shields, then shielding effect is enhanced and written bit pattern sharpness is improved, but writability under high frequency writing deteriorates

Engineering Contradiction:

Improvewritten bit pattern sharpnessVSAvoidwritability under high frequency writing

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The gap structure transitions from a static fixed width to a dynamic adaptive structure using thin magnetic layers whose permeability changes with writing frequency. At low frequencies, the thin magnetic layers provide high permeability for shielding; at high frequencies, their permeability decreases, effectively increasing the gap width to improve writability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The magnetic permeability parameter of the gap structure is changed dynamically based on writing frequency. The thin magnetic layers exhibit frequency-dependent permeability, allowing the gap to adapt its magnetic properties rather than maintaining a fixed physical dimension, thereby resolving the trade-off between shielding and writability.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If larger gap width is used between main pole and surrounding shields, then MP flux release is improved and writability is enhanced, but written bit pattern sharpness deteriorates

Engineering Contradiction:

ImprovewritabilityVSAvoidwritten bit pattern sharpness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The gap structure transitions from a static fixed width to a dynamic adaptive structure using thin magnetic layers whose permeability changes with writing frequency. At low frequencies, the thin magnetic layers provide high permeability for shielding; at high frequencies, their permeability decreases, effectively increasing the gap width to improve writability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The magnetic permeability parameter of the gap structure is changed dynamically based on writing frequency. The thin magnetic layers exhibit frequency-dependent permeability, allowing the gap to adapt its magnetic properties rather than maintaining a fixed physical dimension, thereby resolving the trade-off between shielding and writability.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If fixed gap width structure is used, then device complexity is reduced, but adaptability to varying writing frequencies deteriorates

Engineering Contradiction:

Improvegap structure complexityVSAvoidadaptability to varying writing frequencies

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The gap structure uses a composite material system consisting of non-magnetic material layers and thin magnetic layers. This composite structure combines the advantages of both material types: non-magnetic materials provide structural stability and electrical isolation, while thin magnetic layers provide frequency-adaptive magnetic shielding, enabling the gap to adapt to different writing frequencies without significantly increasing structural complexity.

Inventive Principle:

Principle #40Composite materials

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 adaptable gap structure improves writability across different frequency conditions, enhancing performance for both low and high frequency writing, and is well-suited for thermally assisted magnetic recording (TAMR) and microwave assisted magnetic recording (MAMR) technologies.

Implementation Method 1

the thin magnetic layers can help absorb the gap field and reduce bulky shield magnetic potential, while protecting against write bubble fringing and reducing erase width of an AC field (EWAC)

Methodology Applied

Scientific EffectMagnetic permeability: Magnetism

Implementation Method 2

In low frequency writing, the thin layers will have higher permeability and provide normal shielding. Under high frequency conditions, however, the thin layers will have lower permeability and the effective gap size will become larger.

Methodology Applied

Scientific EffectFrequency-dependent magnetic permeability: Magnetism

Data Source

PatentUS11348605B1Writer with adaptive side gap

Publication Date: 2022.05.31 HEADWAY TECHNOLOGIES INC

AI summary

A PMR (perpendicular magnetic recording) write head configured for thermally assisted magnetic recording (TAMR) and microwave assisted magnetic recording (MAMR) is made adaptive to writing at different frequencies by inserting thin layers of magnetic material into the material filling the side gaps (SG) between the magnetic pole (MP) and the side shields (SS). At high frequencies, the thin magnetic layers saturate and lower the magnetic potential of the bulky side shields.