Split-Ring Resonator NFT for HAMR Spot-Size Control
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Solution Overview
Problem
Current heat-assisted magnetic recording (HAMR) heads face challenges in achieving ultra-small spot-sizes due to broad focusing, which negatively affects the write pole and results in thermal instability of data, limiting storage density.
Innovation Solution
A near-field transducer (NFT) functioning as a split-ring resonator (SRR) with a capacitive and inductive portion is used, focusing light at the capacitive area with minimal impact on the write pole, creating a well-concentrated spot-size on the magnetic media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional MIM NFTs are used for focusing light in HAMR heads, then light focusing capability is achieved, but the spot-size becomes broad and head temperatures increase
Solution Approach 1:
The patent changes the resonant frequency parameters of the NFT by transitioning from a MIM structure to an SRR structure with specific capacitive and inductive portions. This parameter change enables resonance at the desired operating wavelength while achieving better spot-size concentration and reduced thermal effects, directly resolving the contradiction between temperature control and focusing precision
Solution Approach 2:
The NFT is segmented into distinct capacitive and inductive portions within the SRR structure. This segmentation allows independent optimization of each portion's properties to achieve the desired resonant characteristics and focusing performance, enabling better control over spot-size concentration while managing thermal effects
2Stability of the object's composition
If higher magnetic coercivity is used to raise the superparamagnetic limit, then thermal stability of data is improved, but write head requirements become more stringent
Solution Approach 1:
The patent replaces the mechanical/approach of increasing write head magnetic moment materials with an optical field-based solution using SRR NFTs. The resonant enhancement of the optical field provides the necessary heating effect to enable writing on high-coercivity media, thereby substituting complex magnetic head design with a more manageable optical field enhancement approach
3Manufacturing precision
If ultra-small spot-size focusing is attempted with traditional NFTs, then storage density is improved, but the write pole is negatively affected
Solution Approach 1:
The SRR NFT structure concentrates the optical field enhancement locally at the capacitive portion with minimal spatial extent. This local quality approach ensures that the ultra-small spot-size focusing is achieved precisely where needed without extending thermal effects to the write pole, thereby maintaining write pole performance while achieving high storage density
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 a 250% increase in coupling efficiency and reduces head temperatures by 40-50% compared to traditional MIM NFTs, enhancing thermal stability and reliability while lowering writing powers by 50%, resulting in improved data recording capabilities.
Implementation Method 1
The NFT functions as a resonant circuit when in operation. The resonant circuit, which comprises the NFT, is a split-ring resonator (SRR) that has a capacitive portion and an inductive portion.
Implementation Method 2
The NFT is a plasmonic nano-antenna that further focuses the light into an ultra-small spot-size for high-density magnetic recording.
Implementation Method 3
The resonant circuit, which comprises the NFT, is a split-ring resonator (SRR) that has a capacitive portion and an inductive portion.
Implementation Method 4
The resonant circuit, which comprises the NFT, is a split-ring resonator (SRR) that has a capacitive portion and an inductive portion.
Data Source
AI summary
An NFT is used in a HAMR magnetic write head. The NFT functions as a resonant circuit when in operation. The resonant circuit, which comprises the NFT, is a split-ring resonator (SRR) that has a capacitive portion and an inductive portion. The inductance and the capacitance results in a very well focused ultra-small spot-size concentrated on the magnetic media. The focus occurs at the capacitive area of the NFT with minimal to no impact upon the write pole of the HAMR magnetic head.