Planar Plasmon Generator Peg for TAMR Write Head
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Solution Overview
Problem
Current magnetic recording technologies face challenges in achieving high data densities due to the conflicting requirements of a stronger writing field and a smaller write head, which are exacerbated by the thermal instability of small magnetic regions, leading to difficulties in scaling down the optical spot size and maintaining reliable field gradients.
Innovation Solution
A planar plasmon generator (PPG) is integrated with a magnetic write pole to form a thermally assisted magnetic recording (TAMR) structure, utilizing a propagating surface plasmon mode to efficiently transfer thermal energy to the recording medium, with a free-standing or integral peg to confine the near field and improve thermal gradient and scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the write head size is reduced to achieve high areal data densities, then the write head can produce the required spatial definition for high density recording, but the field gradient becomes smaller and the field profile becomes broader
Solution Approach 1:
The patent introduces an optical beam as an intermediary energy source that locally heats the magnetic medium to its Curie temperature, temporarily reducing its coercivity and anisotropy. This allows a smaller write head to effectively write on high-coercivity media by creating a localized soft magnetic region where the write field can operate more efficiently.
Solution Approach 2:
The patent changes the thermal parameter (temperature) of the magnetic medium by applying localized optical heating. By raising the temperature to the Curie point, the magnetic properties (coercivity and anisotropy) are temporarily altered, enabling writing on high-coercivity media with a weaker write field from a smaller head.
2Area of moving object
If optical beam focusing is used to reduce spot size for localized heating, then thermal energy can be concentrated on a smaller region, but manufacturing precision and alignment reliability become more difficult to maintain
Solution Approach 1:
The patent merges the optical heating function with the magnetic write pole structure by integrating the optical beam path with the write head geometry. This integration ensures that the heated region and magnetic field region are spatially aligned, reducing sensitivity to alignment errors and simplifying manufacturing.
Solution Approach 2:
The patent designs the optical spot size to be slightly larger than the magnetic field region, creating an overlap zone where both heating and magnetic field effects are present. This ensures that even with manufacturing tolerances and alignment variations, the critical writing region remains within the heated zone, maintaining reliable operation.
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
The PPG structure effectively reduces the optical spot size and improves linear recording density, enhancing track density and thermal gradient while being compatible with existing fabrication processes, thus addressing the limitations of prior art in scalability and reliability.
Implementation Method 1
transfer of electromagnetic energy to a small, sub-micron sized region of a magnetic medium through interaction of the magnetic medium with the near field of an edge plasmon excited by an optical frequency laser
Implementation Method 2
The heating effect of TAMR works by raising the temperature of a small region of the magnetic medium to essentially its Curie temperature
Implementation Method 3
the optical mode of the incident radiation couples to a propagating edge plasmon mode in the PG, whereby the optical energy is converted into plasmon energy that travels along the PG
Implementation Method 4
When the heated spot on the medium is correctly aligned with the magnetic field produced by the write head pole, TAMR is achieved
Data Source
AI summary
A TAMR (Thermal Assisted Magnetic Recording) write head uses the energy of optical-laser excited surface plasmons in a scalable planar plasmon generator to locally heat a magnetic recording medium and reduce its coercivity and magnetic anisotropy. The planar plasmon generator is formed as a multi-layered structure in which one planar layer supports a propagating surface plasmon mode that is excited by evanescent coupling to an optical mode in an adjacent waveguide. A peg, which can be a free-standing element or an integral projection from one of the layers, is positioned between the ABS end of the generator and the surface of the recording medium, confines and concentrates the near field of the plasmon mode immediately around and beneath it.