HAMR Main Pole Plasmonic Recess for Thermal Gradient
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Solution Overview
Problem
In heat-assisted magnetic recording (HAMR) disk drives, the addition of a full-film plasmonic layer increases the gap between the near-field transducer (NFT) and the main pole, reducing magnetic field intensity and increasing the NFT temperature, which affects thermal gradient and data recording stability.
Innovation Solution
A recess is created in the main pole's surface facing the NFT, containing plasmonic material with a tip aligned along the track direction, reducing the cross-track width and maintaining contact with the NFT, thereby minimizing the gap and temperature increase, while allowing for a localized optical near-field and enhanced thermal gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a full-film plasmonic layer is added on the main pole, then the thermal gradient in the recording layer is increased, but the gap between the NFT and main pole increases, reducing magnetic field intensity
Solution Approach 1:
The plasmonic layer is segmented into a recessed structure rather than a full-film continuous layer. The recess is formed in the main pole surface and filled with plasmonic material, creating a localized plasmonic region that maintains thermal gradient while preserving magnetic field intensity by reducing the overall gap distance.
Solution Approach 2:
The plasmonic material is localized to a specific recess region on the main pole surface rather than covering the entire surface. This localized placement concentrates the plasmonic effect where needed for thermal gradient enhancement while minimizing the impact on magnetic field coupling with the NFT.
2Temperature
If a full-film plasmonic layer is added on the main pole, then the thermal gradient is enhanced, but the NFT temperature increases
Solution Approach 1:
The plasmonic layer is segmented into a recessed structure that confines the plasmonic material to a localized region. This segmentation prevents excessive heat accumulation in the NFT by limiting the plasmonic interaction area, thereby enhancing thermal gradient in the recording layer while controlling NFT temperature rise.
3Object-affected harmful factors
If the cross-track width of the plasmonic tip is reduced, then the NFT temperature is reduced, but the thermal gradient may be compromised
Solution Approach 1:
The plasmonic tip cross-track width is optimized to create the right balance: narrow enough to limit heat transfer to the NFT and reduce its temperature, but sufficiently wide to maintain effective plasmonic coupling with the recording layer for thermal gradient enhancement. The local geometry is precisely controlled to achieve this dual objective.
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 maintains a strong magnetic field intensity and reduces NFT temperature, achieving a high thermal gradient for improved data recording stability and thermal management in HAMR disk drives.
Implementation Method 1
In this NFT an evanescent wave generated at a surface of the waveguide couples to surface plasmons excited on the surface of the NFT
Implementation Method 2
an evanescent wave generated at a surface of the waveguide couples to surface plasmons excited on the surface of the NFT and a strong optical near-field is generated at the apex of the output tip
Implementation Method 3
a strong optical near-field is generated at the apex of the output tip
Implementation Method 4
The plasmonic material includes a plasmonic tip at the main pole output end at the GBS that is aligned with the NFT in the along-the-track direction
Implementation Method 5
By reducing the width of the plasmonic tip at the GBS the NFT temperature can be reduced
Implementation Method 6
A thermal shunt of high thermal conductivity material is located between the NFT and the main pole to allow heat to be transferred away from the optical spot to heat sink material located on the cross-track sides of the main pole
Data Source
AI summary
A heat-assisted magnetic recording (HAMR) head has a slider with a gas-bearing-surface (GBS). The slider supports a near-field transducer (NFT) with an output tip at the GBS and a main magnetic pole that has a recess in the NFT-facing surface that contains plasmonic material. The plasmonic recess has a front edge at the GBS that has a cross-track width equal to or less than the cross-track width of the widest portion of the NFT output tip, and a back edge recessed from the GBS. A thermal shunt is located between the NFT and the main pole to allow heat to be transferred away from the optical spot generated by the NFT output tip, and is in contact with a region of the plasmonic recess near the back edge.