Thermally-Assisted Magnetic Recording Head Pole Segmentation
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Solution Overview
Problem
Current thermally-assisted magnetic recording heads face challenges in achieving a reduced track width while maintaining a sufficient write magnetic field magnitude, as reducing the light spot size leads to increased thermal spot size due to heat conduction, and narrowing the main pole or write pole tip compromises magnetic flux and field strength.
Innovation Solution
A thermally-assisted magnetic recording head design featuring a main pole with a first and second end face portion, where the second end face portion is wider than the first in the track width direction, and side shields positioned to capture and direct magnetic flux, allowing for a larger magnetic flux and sharpened write magnetic field distribution, along with a gap film to manage heat and maintain magnetic flux alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the light spot size is reduced to achieve higher recording density, then the thermal spot size increases due to heat conduction, but this reduces the effective writing area and recording precision
Solution Approach 1:
The main pole is divided into two distinct portions: a first portion with a first end face portion and a second portion with a second end face portion. The second end face portion is wider than the first end face portion in the track width direction. This segmentation allows the narrower first portion to define a smaller light spot size for higher recording density, while the wider second portion compensates for heat conduction spread to maintain adequate thermal spot size for effective writing.
Solution Approach 2:
Different portions of the main pole are given different widths in the track width direction. The first end face portion has a narrower width optimized for small light spot size and high recording density, while the second end face portion has a wider width to compensate for thermal diffusion. This local quality variation allows each portion to serve its specific function optimally.
2Length of moving object
If the main pole width is reduced to achieve smaller track width, then the write magnetic field strength decreases, but this compromises data writing capability
Solution Approach 1:
The main pole is segmented into two portions with different end face widths. The first portion has a narrower end face that defines a small track width for high track density, while the second portion has a wider end face that generates sufficient write magnetic field strength. This segmentation resolves the contradiction between narrow track width and strong magnetic field.
Solution Approach 2:
The main pole exhibits local quality variation along its length, with the first portion having a narrower cross-section for small track width and the second portion having a wider cross-section for strong magnetic field generation. This localized structural differentiation allows simultaneous achievement of small track width and sufficient field strength.
3Force
If the second end face portion is made wider to maintain magnetic flux, then the overall pole width increases, but this may reduce recording density
Solution Approach 1:
The main pole is divided into functional segments where only the second portion has the wider end face for magnetic flux maintenance. The first portion maintains a narrow width for high recording density. This segmentation ensures that the wider section is minimized to only where necessary for magnetic flux, reducing overall impact on recording density.
Solution Approach 2:
The solution addresses the width constraint by utilizing the longitudinal dimension of the main pole. Instead of increasing width uniformly, the wider second end face portion extends along the longitudinal axis, providing sufficient magnetic flux area without increasing the track width direction dimensions that would reduce recording density.
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
This configuration enables a smaller track width and a write magnetic field of sufficient magnitude, enhancing recording density and efficiency by maintaining magnetic flux and heat management, thereby improving linear recording density and reducing thermal spot size.
Implementation Method 1
excite surface plasmons on the plasmon generator by using evanescent light that occurs on the surface of the core based on the light propagating through the core
Implementation Method 2
excite surface plasmons on the plasmon generator based on the light propagating through the core, and to cause near-field light to be generated from the end face of the plasmon generator based on the excited surface plasmons
Implementation Method 3
pass a magnetic flux corresponding to the magnetic field produced by the coil, and to produce from the front end face a write magnetic field for use to write data on the recording medium
Implementation Method 4
a write magnetic field and heat are simultaneously applied to the area of the recording medium where to write data, so that the area rises in temperature and drops in coercivity for data writing
Data Source
AI summary
A thermally-assisted magnetic recording head includes a main pole, a plasmon generator, and first and second side shields. The main pole has a front end face located in the medium facing surface. The plasmon generator has a near-field light generating surface located in the medium facing surface. The front end face of the main pole includes a first end face portion, and a second end face portion greater in width than the first end face portion. The first and second side shields have first and second side shield end faces located on opposite sides of at least part of the near-field light generating surface and at least part of the first end face portion in the track width direction.