Heat-Assisted Magnetic Write Head with Dielectric Clads
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Solution Overview
Problem
Heat-assisted magnetic recording faces challenges in increasing recording density while preventing corrosion of the main magnetic pole due to temperature increases, especially when the plasmon generator is used to generate near-field light, leading to inefficient energy conversion and potential corrosion from moisture.
Innovation Solution
A heat-assisted magnetic write head design featuring a waveguide with specific dielectric clads that increase energy density in the track width direction, positioning the heating spot closer to the magnetic pole for improved recording precision and efficiency, and using a refractive index gradient to concentrate light energy near the magnetic pole, thereby reducing the risk of corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If near-field light is generated using a plasmon generator, then heat can be applied to lower coercivity for recording, but energy conversion efficiency is extremely low and temperature increase in the plasmon generator becomes extremely large
Solution Approach 1:
The patent extracts the light generation function from the plasmon generator and implements it separately using a laser light source. The laser light is then guided through a waveguide to the recording position, separating the heat generation function from the light source, thereby reducing energy loss and temperature increase in the light source component.
Solution Approach 2:
The patent introduces a waveguide as an intermediary component to transmit laser light from the light source to the recording position on the magnetic disk. This waveguide mediator enables efficient light transmission while keeping the light source separate from the heating zone, improving overall system efficiency.
2Quantity of substance
If magnetic microparticles are made small to increase recording density, then higher capacity is achieved, but thermal stability of magnetization is lowered
Solution Approach 1:
The patent changes the physical state of the magnetic recording medium by applying localized heat to temporarily reduce coercivity during writing, and relies on the intrinsic thermal stability of the magnetic microparticles to maintain data retention. This parameter change approach enables high-density recording while preserving thermal stability through controlled temporal variations in magnetic properties.
3Stability of the object's composition
If anisotropic energy is increased to solve thermal stability issues, then magnetization stability improves, but coercivity increases making recording difficult
Solution Approach 1:
The patent employs periodic action by applying laser heat pulses during the writing process to temporarily reduce coercivity. The magnetic field is applied during these periodic heating intervals when coercivity is lowered, enabling recording in high-coercivity media without compromising the inherent magnetization stability provided by high anisotropic energy.
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 enhances recording density by narrowing the write track width and achieves high-efficiency, high-precision heat-assisted magnetic recording while minimizing the risk of magnetic pole corrosion by optimizing energy distribution and placement.
Implementation Method 1
a waveguide 32 extending in a head thickness direction toward the air bearing surface to propagate light
Implementation Method 2
a first pair of clads 33A and 33B made of a first dielectric material with a refractive index lower than that of the waveguide 32, and sandwiching the waveguide 32 in a track width direction
Implementation Method 3
The clads with different refractive indexes concentrate light energy near the magnetic pole
Implementation Method 4
a method using a near-field light probe that is a metal strip generating near-field light from a plasmon which is excited by light, that is, so-called plasmon generator
Implementation Method 5
a magnetic pole 35 having an end surface exposed at the air bearing surface
Implementation Method 6
heat is applied together with the magnetic field to a portion where the information is recorded out of the magnetic recording medium to increase the temperature and to lower the coercivity
Data Source
AI summary
A heat-assisted magnetic write head includes a magnetic pole having an end surface exposed at an air bearing surface, a waveguide extending toward the air bearing surface to propagate light, a first pair of clads made of a first dielectric material having a refractive index lower than that of the waveguide, and sandwiching the waveguide in a track width direction, and a second pair of clads made of a second dielectric material having a refractive index lower than that of the first dielectric material, and sandwiching the waveguide in a thickness direction orthogonal to the track width direction. Further, the heat-assisted magnetic write head may include, between the magnetic pole and the waveguide, a plasmon generator generating near-field light from the air bearing surface, based on light propagating through the waveguide.