Thermally-Assisted Magnetic Recording Head Plasmon Generator Thermal Stability
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Solution Overview
Problem
Thermally-assisted magnetic recording heads face challenges with deformation of plasmon generators due to heat, leading to degradation of recording properties and reduced recording density, especially in areas with small volumes near the air-bearing surface.
Innovation Solution
A thermally-assisted magnetic recording head design featuring a plasmon generator with a first region and a second region, where the second region is coupled with the first region and filled with a metallic layer made of a material with a higher melting temperature, preventing deformation and ensuring efficient near-field light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plasmon generator with small volume is used near the air-bearing surface to enable higher recording density, then recording density is improved, but the plasmon generator deforms due to heat concentration
Solution Approach 1:
The plasmon generator is divided into two distinct regions: a first region with smaller volume near the air-bearing surface for efficient near-field light generation, and a second region with larger volume for heat dissipation and structural stability. This segmentation allows each region to perform its specific function optimally without compromising the other.
Solution Approach 2:
The plasmon generator is constructed using composite material structure combining different metallic materials with different melting points in different regions. The first region uses material optimized for plasmon generation, while the second region uses material with higher melting point for thermal stability, creating a composite structure that balances optical performance and thermal resistance.
2Ease of operation
If heat is applied to the magnetic disk to lower coercivity for information recording, then information recording is enabled, but the plasmon generator overheats and deforms
Solution Approach 1:
The heat-generating function is extracted from the plasmon generator itself and transferred to the magnetic disk. The plasmon generator produces near-field light that heats the magnetic disk locally, rather than heating the plasmon generator directly. This separation allows the plasmon generator to remain cool while achieving the desired thermal effect on the recording medium.
Solution Approach 2:
Near-field light acts as an intermediary between the plasmon generator and the magnetic disk. The plasmon generator converts electrical energy to optical energy (surface plasmon polaritons), which then converts to thermal energy at the magnetic disk surface. This intermediary mechanism allows precise spatial control of heating while keeping the plasmon generator temperature manageable.
3Use of energy by moving object
If the plasmon generator is directly irradiated with light for near-field light generation, then near-field light is generated efficiently, but the plasmon generator overheats and deforms
Solution Approach 1:
The light interaction is moved from direct volumetric heating to surface-confined evanescent field coupling. By using evanescent waves that decay exponentially away from the waveguide surface, the optical energy is confined to a thin region near the plasmon generator surface rather than penetrating deeply into the material, reducing bulk heating while maintaining surface plasmon generation efficiency.
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 design prevents the plasmon generator from receding from the air-bearing surface, enabling higher-density magnetic recording and potentially increasing product lifetime by effectively managing heat and maintaining surface plasmon propagation.
Implementation Method 1
the guided light is coupled with the plasmon generator through evanescent coupling, and surface plasmon polaritons generated on a surface of the plasmon generator are used
Implementation Method 2
surface plasmon polaritons generated on a surface of the plasmon generator are used
Implementation Method 3
a metallic layer filling a part in the second region, and formed essentially of a second metallic material that has a higher melting temperature than a melting temperature of the first metallic material
Data Source
AI summary
The thermally-assisted magnetic recording head includes: a magnetic pole having an end exposed on an air-bearing surface; a waveguide; a plasmon generator formed essentially of a first metallic material, and having a first region and a second region, the first region extending backward from the air-bearing surface to a first position, and the second region being coupled with the first region at the first position and extending backward from the first position; and a metallic layer filling a part in the second region, and formed essentially of a second metallic material that has a higher melting temperature than a melting temperature of the first metallic material.