HAMR Near-Field Transducer with Composite Core-Shell Antenna

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Solution Overview

Problem

In magnetic disk devices using heat-assisted magnetic recording (HAMR) heads, the near-field transducer (NFT) made of gold deforms due to high temperature, leading to atomic diffusion and instability, while using alloys increases NFT temperature and reduces thermal conductivity, necessitating an improved solution.

Innovation Solution

The HAMR head incorporates an antenna with a first portion made of a low-melting-point material like gold and a second portion made of a higher-melting-point material, such as Rh or alloys like AuRh, embedded within the first portion, along with a thermal shunt to manage heat and reduce temperature rise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If gold is used for the NFT material to achieve high optical efficiency, then the optical efficiency is improved, but the NFT deforms due to low melting point at high temperatures

Engineering Contradiction:

Improveoptical efficiencyVSAvoidNFT stability

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent applies composite materials by combining gold with a refractory material to form a core-shell structure. The gold shell maintains high optical efficiency for near-field optical trapping, while the refractory material core provides high-temperature stability and prevents deformation. This composite structure resolves the contradiction between optical efficiency and thermal stability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If an alloy is used for the NFT material to improve temperature stability, then the melting point is improved, but the NFT temperature increases due to reduced thermal conductivity

Engineering Contradiction:

Improvetemperature stabilityVSAvoidNFT operating temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent applies local quality by creating a spatially differentiated structure where the refractory material core provides thermal stability where needed, while the gold shell provides optical functionality at the surface. This localized assignment of material properties allows the NFT to maintain low operating temperature while achieving temperature stability, resolving the contradiction between these two parameters.

Inventive Principle:

Principle #3Local quality

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 reduces the temperature rise of the NFT, lowers the required laser power, and enhances the stability and reliability of the HAMR head by preventing deformation and improving heat flow.

Implementation Method 1

the thermal conductivity of the NFT is lowered due to phonon scattering by dopant atoms, and the heat flow inside the NFT is reduced

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the imaginary part of the dielectric constant is large, and more light is absorbed by the NFT

Methodology Applied

Scientific EffectOptical absorption: Absorption (EM radiation)

Implementation Method 3

a thermal shunt coupled to the antenna

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10636442B2Near-field transducer for heat assisted magnetic recording comprising of thermally stable material layer

Publication Date: 2020.04.28 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

Embodiments disclosed herein generally relate to a HAMR head. The HAMR head includes a main pole, a waveguide and a NFT disposed between the main pole and the waveguide. The NFT includes an antenna, and the antenna includes a first portion and a second portion. The second portion may be made of a material having a higher melting point than the material of the first portion. Having the second portion helps reduce the temperature rise of the NFT and reduce the laser power applied to the NFT.