Thermally-Assisted Recording Head Plasmon-Generator Segmentation
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Solution Overview
Problem
Current thermally-assisted magnetic recording heads face challenges in generating near-field light efficiently while minimizing deformation due to the heating effect, which affects the reduction of the anisotropic field in magnetic recording media, leading to limitations in recording density and thermal stability.
Innovation Solution
A thermally-assisted magnetic recording head design featuring a plasmon-generator with a first PG part made of high thermostability material and a second PG part with high excitation efficiency, positioned to suppress deformation and enhance near-field light generation, where the second PG part is opposed to the waveguide and contacts the side surfaces of the first PG part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a plasmon-generator with metal material is used to generate near-field light, then near-field light generation is achieved, but the metal material deforms due to heating by the near-field light
Solution Approach 1:
The plasmon-generator is divided into two distinct parts: a first plasmon-generator part made of material with high thermostability to resist heating deformation, and a second plasmon-generator part made of material with high plasmon excitation efficiency to generate near-field light. This segmentation allows each part to be optimized for its specific function without compromising the other.
Solution Approach 2:
Different parts of the plasmon-generator are assigned different material properties tailored to their specific functions. The first part uses high-thermostability material localized at positions subject to heating, while the second part uses high-plasmon-efficiency material localized at positions optimized for light excitation and near-field generation.
2Productivity
If magnetic grain size is decreased to increase recording density, then recording density is improved, but thermal stability of magnetization in magnetic grains decreases
Solution Approach 1:
The invention changes the physical state parameter (temperature) of the magnetic recording medium during the writing process. By heating the medium, the anisotropic field is reduced, enabling writing of information even with small magnetic grains that would otherwise be unstable at room temperature. This parameter change allows small grains to maintain thermal stability during normal operation while enabling writing operations.
3Reliability
If magnetic anisotropy energy Ku of magnetic grains is increased to improve thermal stability, then thermal stability is improved, but anisotropic magnetic field (coercive force) of the magnetic recording medium increases
Solution Approach 1:
The invention applies thermal heating temporarily during the writing process to reduce the anisotropic field, performs the writing operation, and then allows the medium to cool back to its original state. This periodic action of heating and cooling enables the use of high-Ku materials that maintain strong anisotropic fields for thermal stability during storage, while temporarily reducing the field during writing when needed.
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 generates near-field light to reduce the anisotropic field of the magnetic recording medium, improving recording density and thermal stability while minimizing deformation, thus enhancing the magnetic recording process.
Implementation Method 1
The plasmon-generator is coupled with light propagating in the waveguide in a surface plasmon mode to excite the surface plasmon, and generates NF light at the near-field light generating portion because the surface plasmon propagates through the plasmon generator
Implementation Method 2
the magnetic recording medium is heated by the NF light generated at the near-field light generating portion of the plasmon-generator, and, after the anisotropic field of the magnetic recording medium is reduced
Implementation Method 3
a magnetic pole that generates the writing magnetic field is established closer to the trailing side than a near-field light generating portion
Data Source
AI summary
A thermally assisted magnetic recording head includes a plasmon-generator that generates near-field light (NF light) from a near-field light generating portion on a near field light generator end surface constituting a portion of the medium opposing surface. The plasmon-generator has a first PG part having the near field light generator end surface constituting a portion of the medium opposing surface, and a second PG part positioned at a back side compared to the medium opposing surface when viewed from the medium opposing surface side. When viewed from the medium opposing surface side, the first PG part extends toward the back side from the medium opposing surface, and the second PG part is placed to contact at least a portion of both side surfaces of the first PG part. A material that configures the first PG part is a material having high thermostability compared to a material that configures the second PG part, and the material that configures the second PG part is a material having high excitation efficiency of plasmon compared to the material that configures the first PG part.