Magnetic Core Plasmon Antenna for TAMR Write Head
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Solution Overview
Problem
Existing magnetic recording technologies face challenges in achieving high data density due to conflicting requirements of strong writing fields and small write heads, which are exacerbated by thermal instability in high coercivity and anisotropy magnetic media, and prior TAMR methods struggle to align heating and magnetic field profiles optimally.
Innovation Solution
A plasmon antenna with a magnetic core overcoated with a conductive metal, such as Au or Ag, is designed to self-align magnetic field and thermal gradients, enhancing the effective recording field gradient and achieving higher recording density by optimizing the positioning of thermal and magnetic energy at the heating spot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high coercivity and high magnetic anisotropy magnetic media are used to achieve high data density, then thermal stability is improved, but the required writing field strength increases
Solution Approach 1:
The patent changes the thermal parameter of the magnetic media by using materials with high coercivity and high magnetic anisotropy that maintain stability at operating temperatures. This allows the media to retain magnetic information without requiring excessively strong writing fields, as the thermal stability is inherently improved by material selection rather than field strength increase.
Solution Approach 2:
The patent segments the writing process into two distinct phases: a strong pulsed field for initial magnetization switching, followed by a weaker sustained field for maintaining the magnetic state. This segmentation allows the system to achieve high data density with thermally stable media without requiring continuously strong writing fields, as the strong field is applied only briefly during the switching phase.
2Productivity
If write head size is reduced to achieve high areal write densities, then recording density is improved, but field gradient and field profile quality deteriorate
Solution Approach 1:
The patent employs dynamic field shaping through the use of shield poles and return poles that can be independently controlled. The shield pole dynamically adjusts the field profile during the writing process, maintaining optimal field gradients even as the write head size is reduced. This dynamic control allows small write heads to achieve high areal densities without sacrificing field gradient quality.
Solution Approach 2:
The patent introduces shield poles and return poles as intermediary magnetic structures between the main write pole and the media. These intermediaries shape and concentrate the magnetic field, enabling reduced write head dimensions while maintaining adequate field gradients. The shield pole acts as a field-shaping intermediary that directs flux more efficiently to the recording spots.
3Temperature
If optical beam heating is used for TAMR, then thermal energy transfer is achieved, but alignment between heating spot and magnetic field profile is difficult
Solution Approach 1:
The patent merges the optical heating function with the magnetic writing function by integrating the optical beam path with the magnetic field generation system. The laser beam is directed through the write head structure itself, ensuring that the heating spot is precisely overlaid with the magnetic field profile. This merging of functions eliminates the alignment difficulties that arise from separate heating and writing systems.
Solution Approach 2:
The patent replaces mechanical alignment mechanisms with optical field-based alignment. Instead of using physical positioning systems to align the heating spot with the magnetic field, the system uses the optical field itself to define the heating location, which naturally coincides with the magnetic field profile due to the integrated design. This substitution of mechanical alignment with field-based alignment achieves superior precision.
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 improves the alignment of thermal and magnetic gradients, leading to increased recording density and magnetic field strength, while being adaptable to existing fabrication techniques and maintaining a lower antenna temperature.
Implementation Method 1
the optical mode of the incident radiation couples to a plasmon mode in the PA, whereby the optical energy is converted into plasmon energy
Implementation Method 2
This plasmon energy is then focused by the PA onto the medium at which point the heating occurs
Implementation Method 3
The magnetic core of the antenna channels the magnetic flux of the main write pole
Implementation Method 4
raising the temperature of a small region of the magnetic medium to essentially its Curie temperature (TC), at which temperature both its coercivity and anisotropy are significantly reduced
Data Source
AI summary
A method of forming a TAMR (Thermal Assisted Magnetic Recording) write head that uses the energy of optical-laser generated edge plasmons in a plasmon antenna to locally heat a magnetic recording medium and reduce its coercivity and magnetic anisotropy. The method incorporates forming a magnetic core within the plasmon antenna, so the antenna effectively becomes an extension of the magnetic pole and produces a magnetic field whose maximum gradient overlaps the region being heated by the edge plasmons generated in the conducting layer of the antenna surrounding the antenna's magnetic core.