Multilayer Near-Field Light Generator for Thermal-Assisted Magnetic Recording
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Solution Overview
Problem
Existing near-field light generators for thermally-assisted magnetic recording heads made of single-layer Au or Ag suffer from reliability issues due to heat concentration, thermal expansion, and deformation, leading to reduced heating performance and potential damage to the recording medium.
Innovation Solution
A multilayer structure with dielectric and metal layers, where each metal layer is separated by dielectric layers of the same permittivity, effectively propagates surface plasmons to the front end face, reducing heat concentration and maintaining structural integrity, thereby enhancing reliability and heating performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single-layer plasmon generator made of Au or Ag is used, then near-field light can be generated, but heat concentrates in the plasmon generator causing thermal expansion and deformation
Solution Approach 1:
The plasmon generator is divided into multiple metal layers (first metal layer and second metal layer) separated by dielectric layers. This segmentation distributes the heat generation across multiple components rather than concentrating it in a single layer, reducing thermal stress and preventing deformation while maintaining the near-field light generation function.
Solution Approach 2:
The invention uses a composite structure combining metal layers (for plasmon generation) and dielectric layers (for thermal isolation and mechanical support). This composite material approach allows the system to benefit from both the optical properties of metals and the thermal properties of dielectrics, improving reliability under thermal conditions.
2Temperature
If the plasmon generator is made of soft metals with high thermal expansion coefficients, then near-field light generation is achieved, but structural integrity deteriorates due to thermal expansion
Solution Approach 1:
By segmenting the metal layer into multiple thinner layers separated by dielectric spacers, the structural stress from thermal expansion is distributed and reduced. Each layer can expand independently within constraints, preventing the cumulative deformation that would occur in a single thick layer.
Solution Approach 2:
Dielectric layers are introduced as intermediary structures between the metal layers. These dielectric layers have low thermal expansion coefficients and serve as buffers that accommodate thermal expansion differences, maintaining the overall structural integrity while allowing the metal layers to function for heat generation.
3Ease of manufacture
If a single-layer metal structure is used, then manufacturing is simplified, but heat concentration reduces heating efficiency and causes damage
Solution Approach 1:
The segmentation into multiple layers, while adding manufacturing steps, enables better heat distribution and prevents heat concentration. The standardized multilayer structure can be manufactured using conventional thin-film deposition techniques, making the increased complexity manageable while achieving superior heating 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
The multilayer structure efficiently propagates surface plasmons to the front end face, preventing heat-induced deformation and damage, thus improving the reliability and heating performance of the near-field light generator in thermally-assisted magnetic recording heads.
Implementation Method 1
the first metal layer propagates a first surface plasmon, the second metal layer propagates a second surface plasmon, and the front end face generates near-field light based on the first and second surface plasmons
Implementation Method 2
a recording medium is irradiated with near-field light to lower the coercivity of the recording medium for data writing
Data Source
AI summary
A near-field light generator includes a multilayer structure having a front end face. The multilayer structure includes a first dielectric layer, a second dielectric layer, a third dielectric layer, a first metal layer, and a second metal layer. The first metal layer is interposed between the first dielectric layer and the second dielectric layer. The second metal layer is interposed between the second dielectric layer and the third dielectric layer. Each of the first to third dielectric layers and the first and second metal layers has an end located in the front end face. The dielectric material used to form the first dielectric layer, the dielectric material used to form the second dielectric layer, and the dielectric material used to form the third dielectric layer have the same permittivity.