Thermally-Assisted Magnetic Recording Head Using Waveguide and Light-Absorbing Layer
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Solution Overview
Problem
Existing thermally-assisted magnetic recording techniques face challenges with near-field light generators, including low light use efficiency, thermal expansion issues, and difficulty in maintaining close proximity to the magnetic recording medium, which affects recording density and stability of magnetization transitions.
Innovation Solution
A thermally-assisted magnetic recording head design that uses a waveguide to guide light for thermal assist, with a main magnetic pole and auxiliary pole configuration, allowing for close proximity and reduced light absorption, enabling stable record bit formation with steep magnetization transitions without relying on near-field light generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a near-field light generator (plasmon antenna) is used to heat the magnetic recording medium, then the anisotropic magnetic field is reduced enabling data writing, but the light use efficiency is low and thermal energy heats the plasmon antenna to extremely high temperatures causing thermal expansion and protrusion
Solution Approach 1:
A light-absorbing layer is introduced as an intermediary between the light source and the magnetic recording medium. This layer absorbs the light energy and converts it to thermal energy, which is then transferred to the magnetic recording medium through thermal conduction. This mediator approach allows efficient heating of the medium while preventing excessive temperature rise in the light source components.
Solution Approach 2:
The patent replaces the direct optical heating mechanism (plasmon antenna converting light to near-field light) with a thermal conduction-based heating mechanism. Instead of using electromagnetic fields directly to heat the medium, the system uses a light-absorbing layer to convert optical energy to thermal energy, which is then conducted thermally to the magnetic recording medium.
2Temperature
If the plasmon antenna is heated to extremely high temperatures, then the magnetic recording medium can be heated, but the plasmon antenna thermally expands and protrudes from the opposed-to-medium surface toward the magnetic recording medium
Solution Approach 1:
A light-absorbing layer is introduced as an intermediary between the light source and the magnetic recording medium. This layer absorbs the light energy and converts it to thermal energy, which is then transferred to the magnetic recording medium through thermal conduction. This mediator approach allows efficient heating of the medium while preventing excessive temperature rise in the light source components.
Solution Approach 2:
The patent replaces the direct optical heating mechanism (plasmon antenna converting light to near-field light) with a thermal conduction-based heating mechanism. Instead of using electromagnetic fields directly to heat the medium, the system uses a light-absorbing layer to convert optical energy to thermal energy, which is then conducted thermally to the magnetic recording medium.
3Temperature
If the plasmon antenna protrudes toward the magnetic recording medium, then thermal energy is transferred, but the read head element becomes far apart from the magnetic recording medium making it difficult to properly read the servo signal
Solution Approach 1:
A light-absorbing layer is introduced as an intermediary between the light source and the magnetic recording medium. This layer absorbs the light energy and converts it to thermal energy, which is then transferred to the magnetic recording medium through thermal conduction. This mediator approach allows efficient heating of the medium while preventing excessive temperature rise in the light source components.
Solution Approach 2:
The head structure is segmented into distinct functional zones: a light source unit for thermal assist, a write head element for data writing, and a read head element for data reading. The light source is positioned on the leading side while the write and read elements are on the trailing side, allowing independent optimization of each function without interference.
4Stability of the object's composition
If the anisotropic magnetic field of the magnetic recording medium is increased to stabilize magnetization, then thermal stability is improved, but the write field intensity of the thin-film magnetic head becomes insufficient to write data
Solution Approach 1:
The patent changes the temperature parameter of the magnetic recording medium dynamically during the writing process. By locally heating the medium with a light-absorbing layer, the anisotropic magnetic field is reduced in the heated region, allowing the write head to successfully write data even when the overall medium has high anisotropic magnetic field for stable magnetization.
Solution Approach 2:
The system uses pulsed or localized heating action followed by immediate writing. The light source is activated to heat the light-absorbing layer and the magnetic recording medium in a controlled manner, and the write head applies the write field during or immediately after this thermal pulse, creating a time-dependent writing process.
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 design achieves high linear recording density and stable magnetization transitions by optimizing the waveguide and magnetic pole configuration, suppressing light absorption and maintaining sufficient write field intensity, thus improving recording performance.
Implementation Method 1
a waveguide for guiding light from a light source to the magnetic recording medium
Implementation Method 2
a write head element on a trailing side from the waveguide and including a magnetic pole for applying a magnetic field to the magnetic recording medium
Implementation Method 3
a light-absorbing layer formed on an opposite side to the element-formation surface side of the magnetic recording medium
Implementation Method 4
a magnetic recording medium formed of a magnetic material with a large energy KU is used so as to stabilize the magnetization; anisotropic magnetic field of the medium is reduced by applying heat to a portion of the medium
Data Source
AI summary
A head capable of favorite thermally-assisted magnetic recording without depending on the use of a near-field light generator is provided. The head comprises a write head element formed on the trailing side from a waveguide and comprising a first main pole. The first main pole and the waveguide are opposed to each other through a first clad layer, and a second clad layer is provided on a rear side from the first main pole. This gives that the end surface of the waveguide can be placed much close to the end surface of the first main pole apart by only a thickness of the first clad layer. As a result, the end surface of the first main pole can apply a sufficient intensity of write field to the intensity center and its vicinity of the light spot formed on the magnetic recording layer.