Recessed Write Gap Structure for Higher Bias Current in PMR Heads
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Solution Overview
Problem
Existing magnetic write heads in hard-disk-drive (HDD) devices face limitations in maximizing data capacity due to degraded performance in shrinking write heads operating at GHz frequencies, necessitating improvements in current-assisted areal density capacity (ADC) gain.
Innovation Solution
A magnetic write head structure with a non-magnetic write gap and additional recessed conductive material beyond the extended throat height, combined with magnetic 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
1Quantity of substance
If the write head size is reduced to increase data capacity, then the areal density capacity increases, but the performance degrades due to limited bias current flow
Solution Approach 1:
The patent extends the write gap material vertically beyond the extended throat height (eTHd) of the hot seed layer, adding a third dimension to the current flow path. This vertical extension increases the electrical contact area between the write gap material and the main pole, allowing sufficient bias current to flow even in miniaturized write heads, thus resolving the performance degradation issue while maintaining high data capacity
Solution Approach 2:
The patent changes the geometric parameters of the write gap structure by extending its height beyond the eTHd level and optimizing its thickness (17-25 nm). This parameter modification increases the electrical contact area and reduces device resistance, enabling adequate bias current flow in scaled-down write heads without sacrificing the increased areal density capacity
2Power
If the electrical contact area is increased to allow more bias current flow, then the maximum allowable bias current increases, but the device resistance increases
Solution Approach 1:
The patent optimizes the write gap material thickness to a specific range (17-25 nm) and extends its vertical height beyond the eTHd level. This controlled parameter change increases the horizontal electrical contact area while managing the vertical dimension, thereby reducing device resistance and enabling higher bias current flow without excessive energy loss
Solution Approach 2:
The patent employs a composite structure consisting of the write gap material (non-magnetic conductive layer) in conjunction with the hot seed layer and main pole. This composite arrangement creates multiple parallel current paths and enhances the overall electrical contact area, reducing device resistance while facilitating increased bias current flow to the magnetic recording medium
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 enhances the maximum allowable bias current, leading to a 79% increase in current-assisted areal density capacity gain, improving HDD performance and data storage capabilities.
Implementation Method 1
The WG can include a non-magnetic electrical conductor
Implementation Method 2
a main pole (MP) configured to provide a magnetic flux to a recording medium
Implementation Method 3
a trailing shield (TS) comprising a hot seed (HS) and write shield (WS) to collect a portion of the flux from the MP
Implementation Method 4
a side shield (SS), a leading shield (LS), and a write shield (WS), each comprising a magnetic material that prevents magnetic flux from reaching the medium bits away from the MP
Implementation Method 5
a height of the WG is greater than an eTHd height of the HS, which is configured to 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.