HAMR Overcoat Heat Dissipation Layer for DLC Protection
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Solution Overview
Problem
The diamond-like carbon (DLC) overcoat in heat-assisted magnetic recording (HAMR) media degrades at high temperatures, leading to potential data corruption and reduced thermal gradients, which are critical for high-density magnetic recording.
Innovation Solution
A non-magnetic multilayered overcoat comprising a heat-dissipation layer with high thermal conductivity, a DLC layer, and an optional interface layer with low thermal conductivity is used to manage heat distribution, reducing the DLC overcoat temperature without affecting the recording layer's thermal gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DLC overcoat is used to protect the FePt recording layer, then corrosion protection and damage resistance are improved, but the overcoat degrades at high temperatures during HAMR writing
Solution Approach 1:
A heat-dissipation layer is introduced as an intermediary between the DLC overcoat and the FePt recording layer. This layer acts as a thermal mediator that conducts heat away from the DLC overcoat, preventing it from reaching degradation temperatures while allowing the FePt recording layer to reach the high temperatures needed for magnetic switching.
Solution Approach 2:
The protective overcoat structure is segmented into multiple functional layers: the DLC overcoat for protection, the heat-dissipation layer for thermal management, and optionally an interface layer for adhesion and optical properties. This segmentation allows each layer to perform its specific function without interfering with others, particularly protecting the DLC from thermal damage.
2Temperature
If heat is dissipated from the DLC overcoat, then DLC degradation is prevented, but the thermal gradient in the recording layer may be reduced
Solution Approach 1:
The heat-dissipation layer provides localized thermal management at the DLC-FePt interface. Heat is dissipated locally from the DLC overcoat where it would cause degradation, while the overall thermal gradient in the FePt recording layer is maintained through controlled heat conduction paths and the specific thermal conductivity properties of the heat-dissipation layer.
Solution Approach 2:
The thermal conductivity parameter of the heat-dissipation layer is carefully selected to balance two competing requirements: sufficient thermal conductivity to protect the DLC from overheating, but not so high as to eliminate the thermal gradient needed for HAMR writing. This parameter optimization allows simultaneous achievement of DLC protection and thermal gradient maintenance.
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 multilayered overcoat effectively reduces the DLC overcoat temperature by laterally spreading heat, maintaining the thermal gradient necessary for high-density magnetic recording while preventing DLC degradation.
Implementation Method 1
The heat-dissipation layer is a material with relatively high in-plane thermal conductivity, substantially higher than the in-plane thermal conductivity of both the DLC layer and the recording layer. The heat-dissipation layer laterally spreads the heat generated in the DLC layer by absorption of light from the NFT
Implementation Method 2
The interface layer increases the thermal resistance between the recording layer and the heat-dissipation layer
Implementation Method 3
The heat-dissipation layer laterally spreads the heat generated in the DLC layer by absorption of light from the NFT
Data Source
AI summary
A heat-assisted magnetic recording (HAMR) medium has a non-magnetic multilayered overcoat on the recording layer. The overcoat includes a heat-dissipation layer, a diamond-like carbon (DLC) layer on and in contact with the heat-dissipation layer, and an optional interface layer between and in contact with the recording layer and the heat-dissipation layer. The heat-dissipation layer is a material with relatively high in-plane thermal conductivity, substantially higher than the in-plane thermal conductivity of both the DLC layer and the recording layer. The heat-dissipation layer laterally spreads the heat generated in the DLC layer by absorption of light from the near-field transducer to thereby reduce the temperature of the DLC layer. The optional interface layer is a material with relatively low thermal conductivity and increases the thermal resistance between the recording layer and the heat-dissipation layer.