Thermally-Assisted Recording Head Plasmon Generator Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In thermally-assisted magnetic recording, the plasmon generator used to generate near-field light for heating magnetic recording media experiences excessive temperature increases, leading to thermal expansion and potential collision with the recording medium, which can result in reduced reliability and stability of the recording head.
Innovation Solution
A thermally-assisted magnetic recording head is designed with a plasmon generator that has a cross-sectional area gradually decreasing towards the depth side from the air bearing surface, reducing its volume and minimizing projection from the air bearing surface, and is configured with Au, Ag, or Cu materials to suppress thermal expansion effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the plasmon generator is made with high thermal expansion material (Au, Ag, Cu) to improve near-field light generation efficiency, then the near-field light generation efficiency is improved, but the thermal expansion causes the plasmon generator to project from the air bearing surface and potentially collide with the recording medium
Solution Approach 1:
The patent changes the physical parameters of the plasmon generator by selecting materials with specific thermal expansion coefficients (Au, Ag, Cu) and controlling the generator's dimensions (length 0.6-1.8μm, width 0.05-0.15μm, thickness 0.03-0.08μm) to optimize the balance between near-field light generation efficiency and thermal expansion control, ensuring the generator remains within acceptable projection limits
Solution Approach 2:
The patent explicitly addresses thermal expansion by selecting plasmon generator materials (Au, Ag, Cu) known for their thermal properties and designing the generator with specific dimensional constraints to accommodate thermal expansion while preventing excessive projection from the air bearing surface that would cause collision with the recording medium
2Reliability
If the plasmon generator volume is reduced to minimize projection from the air bearing surface, then the flying stability is improved, but the near-field light generation capability may be reduced
Solution Approach 1:
The patent optimizes the plasmon generator's dimensional parameters (length 0.6-1.8μm, width 0.05-0.15μm, thickness 0.03-0.08μm) to achieve the smallest possible volume that maintains sufficient near-field light generation capability while ensuring the generator does not project excessively from the air bearing surface, thereby maintaining flying stability
3Productivity
If the magnetic microparticles are reduced in size to increase recording density, then the recording density is improved, but the thermal stability of magnetizations decreases
Solution Approach 1:
The patent utilizes thermal phase transition principles by heating the magnetic recording medium immediately before applying the writing magnetic field, temporarily reducing the anisotropic magnetic field through thermal energy input, enabling successful writing on high-Ku materials with small magnetic microparticles that would otherwise be too stable to write
Solution Approach 2:
The patent changes the temperature parameter of the magnetic recording medium dynamically - maintaining it at normal operating temperature for stable magnetization during storage, then temporarily increasing it through laser heating before writing to reduce the anisotropic magnetic field, enabling high recording density with small magnetic microparticles
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 the chronological degradation of output and ensures high and long-term reliability of thermally-assisted recording by minimizing the plasmon generator's projection from the air bearing surface, preventing collisions and maintaining flying stability.
Implementation Method 1
a plasmon generator that surface-evanescent-couples with the light propagating through the waveguide
Implementation Method 2
a transmit part for transmitting plasmon generated on a surface to the air bearing surface as being closely-aligned with the waveguide and generates near-field light from a near-field light generating end surface
Implementation Method 3
another method (near-field light heating) in which laser light is converted to near-field light to heat the medium
Implementation Method 4
configured with Au, Ag, or Cu materials to suppress thermal expansion effects
Data Source
AI summary
A thermally-assisted magnetic recording head that includes a pole that generates a writing magnetic field, a waveguide through which light propagates, a plasmon generator that surface-evanescent-couples with the light propagating through the waveguide, wherein the plasmon generator includes a portion where a cross-sectional area gradually decreases as going toward a depth side from an air bearing surface when being observed from a cross section parallel to the air bearing surface. The volume of the plasmon generator can be decreased and an exposed area of a front surface on the air bearing surface can be increased. When a thermal expansion from the temperature increase occurs in the plasmon generator, a rate that the plasmon generator projects from the air bearing surface is suppressed to extremely low levels. Accordingly, a chronological degradation of output can be suppressed and thermally-assisted recording having a high and long-term reliability is achieved.