Composite Plasmon Generator for Magnetic Head Hardness
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Solution Overview
Problem
Plasmon generators formed entirely of Au or Ag in thermally-assisted magnetic recording heads face issues with reliability due to softness, thermal expansion, and degradation, leading to reduced heating performance and potential damage to the recording medium.
Innovation Solution
A plasmon generator with a first portion made of a high electrical conductivity metal and a second portion made of a higher Vickers hardness metal, featuring an inclined surface and a wedge-shaped structure to efficiently propagate surface plasmons to the front end face, preventing mechanical deformation and maintaining heating performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plasmon generator is formed entirely of Au or Ag, then the electrical conductivity is high and surface plasmons can be excited efficiently, but the Vickers hardness is low causing mechanical deformation during polishing and etching
Solution Approach 1:
The plasmon generator is constructed as a composite structure with a first portion made of a first metal material (high electrical conductivity, e.g., Au or Ag) and a second portion made of a second metal material (higher Vickers hardness, e.g., W, Mo, or Pt). This composite structure allows the first portion to efficiently excite surface plasmons while the second portion provides mechanical strength and resistance to deformation during polishing and etching processes.
2Reliability
If the plasmon generator is formed entirely of Au or Ag, then the surface plasmon excitation efficiency is high, but the thermal expansion coefficient is high causing protrusion toward the recording medium during operation
Solution Approach 1:
The second portion made of a second metal material with lower thermal expansion coefficient than the first metal material compensates for the thermal expansion of the first portion during operation. This differential thermal expansion design prevents the plasmon generator from protruding toward the recording medium while maintaining the heating performance provided by the first portion.
Solution Approach 2:
Different portions of the plasmon generator have different material properties optimized for their specific functions: the first portion (where surface plasmons are excited) has high electrical conductivity for efficient plasmon generation, while the second portion (providing structural support) has low thermal expansion coefficient for dimensional stability during thermal cycling.
3Reliability
If the front end face of the plasmon generator is significantly recessed from the medium facing surface, then the mechanical deformation is reduced, but the heating performance is degraded due to increased distance from the recording medium
Solution Approach 1:
The second portion with higher Vickers hardness prevents significant recession of the front end face during polishing and etching, while the inclined surface design ensures the front end face remains at an optimal distance from the recording medium for effective heating performance.
4Manufacturing precision
If polishing and etching are performed to remove smears, then the surface quality is improved, but the front end face becomes significantly recessed due to softness of Au or Ag
Solution Approach 1:
The second portion made of a second metal material with higher Vickers hardness provides resistance to polishing and etching, preventing significant recession of the front end face while still allowing surface quality improvement through controlled polishing and etching processes.
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 solution provides a plasmon generator of high reliability, ensuring efficient propagation of surface plasmons and maintaining heating performance, thus enhancing the thermally-assisted magnetic recording head's reliability and data writing capabilities.
Implementation Method 1
a plasmon exciting part configured to excite a surface plasmon thereon through coupling with evanescent light generated from a core through which light propagates
Implementation Method 2
Surface plasmons are excited on the plasmon generator and propagate along the surface of the plasmon generator to reach the front end face
Implementation Method 3
the surface plasmons concentrate at the front end face, and near-field light is generated from the front end face based on the surface plasmons
Implementation Method 4
The second metal material is higher in Vickers hardness than the first metal material
Implementation Method 5
The second portion is located between the inclined surface and the front end face, and includes a first end face located in the front end face and a second end face in contact with the inclined surface
Data Source
AI summary
A plasmon generator has a front end face located in a medium facing surface of a magnetic head. The plasmon generator includes a first portion formed of a first metal material and a second portion formed of a second metal material. The first portion has an inclined surface facing toward the front end face. The second portion is located between the inclined surface and the front end face, and includes a first end face located in the front end face and a second end face in contact with the inclined surface. The second metal material is higher in Vickers hardness than the first metal material. The first portion has a plasmon exciting part. The front end face generates near-field light.