Recessed Write Gap Structure for Higher Bias Current in Magnetic Write Heads
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Solution Overview
Problem
Existing magnetic write heads in hard-disk-drives face limitations in scaling and performance degradation due to degraded writability and limited maximum allowable bias current, which restricts the areal density capacity (ADC) gain.
Innovation Solution
A magnetic write head structure with a non-magnetic write gap and additional recessed conductive material extending beyond the extended throat height (eTHd) height, combined with magnetic side and leading shields, enhances the electrical contact area for bias current flow, reducing device resistance and increasing the maximum allowable bias current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the write gap height is increased to extend beyond the eTHd height of the hot seed layer, then the electrical contact area between the hot seed and main pole increases for bias current flow, but the device complexity increases due to additional recessed conductive material structure
Solution Approach 1:
The write gap material extends in the vertical dimension beyond the eTHd height of the hot seed layer, creating a recessed portion that provides additional electrical contact area. This dimensional extension allows bias current to flow through a larger cross-sectional area, reducing device resistance and increasing the maximum allowable bias current without fundamentally redesigning the entire write head structure.
Solution Approach 2:
The recessed write gap material creates an additional electrical pathway that copies the current flow function of the hot seed layer, providing redundant current flow paths. This ensures reliable bias current injection even when the hot seed layer dimensions are constrained by thermal diffusion requirements.
2Reliability
If heat-assisted magnetic recording (HAMR) is used to increase data capacity, then the writability of the magnetic recording medium is improved, but the device complexity increases due to additional heating mechanisms
Solution Approach 1:
The write head combines conventional magnetic writing components (main pole, shields, write gap) with HAMR heating components (hot seed layer, resistive heating path) into a single integrated structure. The hot seed layer serves dual purposes: as a magnetic shield component and as a resistive heating element for HAMR, eliminating the need for separate heating mechanisms and reducing overall device complexity.
Solution Approach 2:
The hot seed layer performs multiple functions simultaneously: it acts as a magnetic flux return path, provides resistive heating for HAMR, and serves as an electrical contact for bias current injection. This multi-functionality reduces the number of separate components needed, simplifying the overall write head structure while enabling both conventional and heat-assisted magnetic recording.
3Reliability
If the write gap material thickness is increased to reduce device resistance, then the maximum allowable bias current increases, but the manufacturing precision requirements increase
Solution Approach 1:
The write gap material is segmented into two distinct portions: a first portion with uniform thickness that extends from the air-bearing surface to the eTHd height, and a second recessed portion that extends beyond the eTHd height. This segmentation allows each portion to be optimized independently - the first portion provides stable, easy-to-manufacture geometry, while the second portion provides the additional resistance reduction benefit.
Solution Approach 2:
The write gap material has different properties in different regions: the first portion has uniform thickness for manufacturing simplicity, while the second recessed portion has increased thickness or extended height to provide additional electrical contact area. This local variation in geometry allows the structure to achieve low resistance without requiring high precision throughout the entire write gap.
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 proposed structure significantly reduces device resistance and enhances the maximum allowable bias current, leading to a substantial increase in current-assisted areal density capacity (ADC) gain, improving write head performance and reliability.
Implementation Method 1
The WG can include a non-magnetic electrical conductor
Implementation Method 2
a magnetic main pole (MP) configured to provide a magnetic flux to a recording medium
Implementation Method 3
a trailing shield (TS) made of magnetic material that collects back the magnetic flux
Implementation Method 4
a side shield (SS), a leading shield (LS), and a write shield (WS) made of magnetic materials that prevent magnetic flux from reaching the medium bits away from the MP tip
Implementation Method 5
The WG can include a height that is greater than an eTHd height of the HS that can increase an electrical contact area between the HS and MP for a bias current flow
Data Source
AI summary
The present embodiments relate to a magnetic write head structure that improves the maximum allowable bias current to maximize the current-assisted areal density capacity (ADC) gain in hard-disk-drive storage device. The write head can include a magnetic main pole (MP) and a trailing shield (TS) made of magnetic material that collects back the magnetic flux and a write gap (WG) between the MP and the TS that is comprised of a non-magnetic electrical conductor. The WG can include a height that is greater than an eTHd height of the HS that can increase an electrical contact area between the HS and MP for a bias current flow. The WG can further include a first part extending an air-bearing surface (ABS) plane of the write head to a top of the eTHd height and a second part extending from the top of the eTHd height.