Thermally-Assisted Magnetic Head Plasmon Generator Segmentation
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Solution Overview
Problem
Conventional thermally-assisted magnetic recording heads face challenges in suppressing migration due to temperature increases in the plasmon generator, leading to reduced output and efficiency in recording density.
Innovation Solution
A thermally-assisted magnetic head is designed with a plasmon generator configured in a V-shape, featuring a first part on the air bearing surface made of high melting point material and a second part made of material with a small imaginary component of permittivity, reducing propagation loss and migration, and incorporating a diffusion layer between dissimilar metals for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the magnetic microparticles are reduced in size to increase recording density, then the recording density is improved, but the thermal stability of magnetization in the magnetic microparticles decreases
Solution Approach 1:
The patent changes the physical state and parameters of the magnetic recording medium by heating it to elevated temperatures during the recording process. This temporary parameter change reduces the coercive force of the magnetic microparticles, enabling successful recording despite their small size and reduced thermal stability. After recording, the medium cools and regains its thermal stability.
Solution Approach 2:
The patent utilizes a phase transition in the magnetic properties of the recording medium by transitioning from a high-coercive-force state at room temperature to a low-coercive-force state at elevated temperatures. This phase transition enables the recording process to overcome the thermal stability limitations of small magnetic microparticles.
2Stability of the object's composition
If the anisotropy energy of the magnetic microparticles is increased to improve thermal stability, then the thermal stability of magnetization is improved, but the coercive force of the magnetic recording medium increases
Solution Approach 1:
The patent temporarily changes the temperature parameter of the magnetic recording medium during recording to reduce coercive force. This allows the use of magnetic microparticles with high anisotropy energy and high thermal stability without suffering from excessively high coercive force, as the reduced temperature during recording overcomes this barrier.
3Reliability
If a laser light source is used to heat the magnetic recording medium for thermally-assisted recording, then the recording capability is improved, but the plasmon generator experiences excessive temperature increase and migration
Solution Approach 1:
The patent segments the plasmon generator into two distinct parts: a first part made of high melting point material positioned on the air bearing surface, and a second part made of material with small imaginary component of permittivity positioned away from the air bearing surface. This segmentation allows each part to perform its specific function while resisting the harmful effects of temperature increase and migration.
Solution Approach 2:
The patent employs composite materials in the plasmon generator structure, combining materials with different properties: high melting point material for thermal resistance at the air bearing surface, and low imaginary component material for reduced propagation loss in the light propagation path. This composite structure optimizes both thermal stability and optical performance.
4Loss of energy
If the plasmon generator is made of material with small imaginary component of permittivity to reduce propagation loss, then the energy efficiency is improved, but the material may experience migration due to temperature increase
Solution Approach 1:
The patent divides the plasmon generator into two parts with different material properties positioned at different locations. The second part (away from air bearing surface) uses material with small imaginary component for low propagation loss, while the first part (on air bearing surface) uses high melting point material for thermal stability, thus combining the benefits of both material types.
Solution Approach 2:
The patent applies different material qualities to different parts of the plasmon generator based on local requirements: low imaginary component material where optical performance is critical (away from air bearing surface), and high melting point material where thermal resistance is critical (on air bearing surface). This local optimization resolves the contradiction between energy efficiency and migration resistance.
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 effectively suppresses migration and power reduction in the plasmon generator, maintaining high recording density and efficiency while preventing excessive temperature increases, thereby enhancing the thermally-assisted magnetic head's performance.
Implementation Method 1
a method utilizing a so-called plasmon antenna, which is a metal referred to as a near-field light probe that generates near-field light from light-excited plasmon
Implementation Method 2
converting laser light to near-field light (a near-field light heating)
Implementation Method 3
a magnetic recording head including an inductive-type electromagnetic transducer (a magnetic recording element) for writing
Implementation Method 4
heat as well as the magnetic field is applied to a portion, to which information is recorded, of the magnetic recording medium when recording the information
Data Source
AI summary
A thermally-assisted magnetic head that includes an air bearing surface facing a recording medium and that performs magnetic recording while heating the recording medium includes: a magnetic recording element including a pole of which one edge part is positioned on the air bearing surface and that generates magnetic flux traveling toward the magnetic recording medium; a waveguide configured with a core through which light propagates and a cladding, at least one part of which extends to the air bearing surface, surrounding the periphery of the core; a plasmon generator that faces a part of the core and that extends to the air bearing surface. The plasmon generator is configured with a first part and a second part that are joined; the first part that is positioned on the air bearing surface side and that is made of a high melting point material, and the second part that is positioned away from the air bearing surface and that is made of a material with a small value ∈″, which is an imaginary component of permittivity.