Use of an embedded contact sensor to study nanoscale heat transfer in heat assisted magnetic recording

2017 ◽  
Vol 110 (3) ◽  
pp. 033104 ◽  
Author(s):  
Haoyu Wu ◽  
David Bogy
Keyword(s):  
Heat Transfer ◽  
Magnetic Recording ◽  
Heat Assisted Magnetic Recording ◽  
Nanoscale Heat Transfer ◽  
Contact Sensor

Experimental Study of Nanoscale Head-Disk Heat Transfer In Heat-Assisted Magnetic Recording

2021 ◽  
Author(s):  
Qilong Cheng ◽  
David B. Bogy
Keyword(s):  
Heat Transfer ◽  
Silicon Wafer ◽  
Magnetic Recording ◽  
Laser Exposure ◽  
Heat Assisted Magnetic Recording ◽  
Contact Sensor ◽  
Higher Temperature ◽  
Dc Current ◽  
Fly Height ◽  
Head Temperature

Abstract To study the nanoscale heat transfer and laser-related protrusions in heat-assisted magnetic recording (HAMR), we performed static touchdown experiments between HAMR waveguide heads and non-rotating media such as a silicon wafer and a recording disk with an AlMg substrate. During the static touchdown, the laser element is energized with DC current and the embedded contact sensor (ECS) is used to monitor the head temperature. The experimental results show that the thermal fly-height control (TFC) touchdown power decreases with increasing laser current. Meanwhile, the head temperature increases due to the laser heating. From this the ECS resistance rise induced by the laser is extracted. The results show that the silicon wafer dissipates heat effectively under the laser exposure, while the AlMg-substrate disk undergoes a higher temperature rise, which in turn heats the head.

A Numerical Study of the Nanoscale Heat Transfer in the Head-Disk Interface for Heat Assisted Magnetic Recording

2016 ◽  
Author(s):  
Haoyu Wu ◽  
David Bogy
Keyword(s):  
Heat Transfer ◽  
Magnetic Recording ◽  
Transfer Problem ◽  
Numerical Study ◽  
Near Field ◽  
Experimental Result ◽  
Head Disk Interface ◽  
Heat Assisted Magnetic Recording ◽  
Disk Interface ◽  
Nanoscale Heat Transfer

The near field transducer (NFT) overheating problem is an issue the hard disk drive (HDD) industry has faced since heat-assisted magnetic recording (HAMR) technology was first introduced. In this paper, a numerical study of the head disk interface (HDI) is performed to predict the significance of the nanoscale heat transfer due to the back heating from the disk. A steady-state heat transfer problem is first solved to get the disk temperature profile. Then an iterative simulation of the entire HDI system is performed. It shows that the heat transfer coefficient in the HDI increases to about 6:49 × 106 W/(m2K) when the clearance is 0:83 nm. It also shows that in the free space laser scenario, the simulation result is close to the experimental result.

A Heat Transfer Study in the Head Disk Interface and an Insight to Heat Assisted Magnetic Recording Design

2017 ◽  
Author(s):  
Haoyu Wu ◽  
David Bogy
Keyword(s):  
Heat Transfer ◽  
Magnetic Recording ◽  
Convective Heat Transfer Coefficient ◽  
Head Disk Interface ◽  
Heat Assisted Magnetic Recording ◽  
Disk Interface ◽  
Height Control ◽  
Contact Sensor ◽  
Series Of Experiments ◽  
Fly Height

Understanding the heat transfer in the head disk interface (HDI) in the heat assisted magnetic recording (HAMR) is important. In this paper, we report on a series of experiments to study the heat transfer in the HDI using the perpendicular magnetic recording (PMR) heads and media. The temperature increase of the embedded contact sensor (ECS) and the thermal fly-height control (TFC) heater was compared in the fly setup and non-fly setup. A series of simulations were performed to explain the results. We show that the design of the air bearing surface can significantly affect the pressure distribution in the read/write transducer area, and thereby affect the convective heat transfer coefficient.

Head flying characteristics in heat assisted magnetic recording considering various nanoscale heat transfer models

2018 ◽  
Vol 123 (3) ◽  
pp. 034303 ◽  
Author(s):  
Yueqiang Hu ◽  
Haoyu Wu ◽  
Yonggang Meng ◽  
Yu Wang ◽  
David Bogy
Keyword(s):  
Heat Transfer ◽  
Magnetic Recording ◽  
Heat Assisted Magnetic Recording ◽  
Nanoscale Heat Transfer ◽  
Transfer Models

Nanoscale heat transfer in the head-disk interface for heat assisted magnetic recording

2016 ◽  
Vol 108 (9) ◽  
pp. 093106 ◽  
Author(s):  
Haoyu Wu ◽  
Shaomin Xiong ◽  
Sripathi Canchi ◽  
Erhard Schreck ◽  
David Bogy
Keyword(s):  
Heat Transfer ◽  
Magnetic Recording ◽  
Head Disk Interface ◽  
Heat Assisted Magnetic Recording ◽  
Disk Interface ◽  
Nanoscale Heat Transfer

Head Disk Spacing Effect on Heat Transfer in Heat Assisted Magnetic Recording

2017 ◽  
Author(s):  
Shaomin Xiong ◽  
Erhard Schreck ◽  
Sripathi Canchi
Keyword(s):  
Heat Transfer ◽  
Magnetic Recording ◽  
Spacing Effect ◽  
Disk Drive ◽  
Heat Assisted Magnetic Recording ◽  
Heating Source ◽  
Spacing Effects ◽  
Thermal Sensing ◽  
Transfer Mechanisms ◽  
Disk Spacing

Heat transfer at nanometer scale attracts a lot of interest from both academia and industries. The hard disk drive (HDD) industry cares about the heat transfer between the head and disk, as several heating and thermal sensing elements are integrated into the HDD system. Understanding the heat transfer mechanism and its dependency on spacing becomes very critical for heat assisted magnetic recording (HAMR). In this paper, we propose a new method to study the head disk spacing effects on heat transfer by introducing a small perturbation to the spacing while maintaining the heating source unchanged. The dependency of heat transfer on the nanoscale spacing provides insights to the understanding of heat transfer mechanisms inside the nanoscale gap.

A Numerical Investigation of the Nanoscale Heat Transfer in Heat Assisted Magnetic Recording

2017 ◽  
Author(s):  
Yueqiang Hu ◽  
Haoyu Wu ◽  
Yonggang Meng ◽  
David Bogy
Keyword(s):  
Heat Transfer ◽  
Magnetic Recording ◽  
Near Field ◽  
Field Analysis ◽  
Management Problem ◽  
Heat Management ◽  
Heat Assisted Magnetic Recording ◽  
The Media ◽  
Em Field

The heat management problem in the heat assisted magnetic recording (HAMR) has been a long-term issue. In this paper, we investigated the temperature increase of a “lollipop” type near field transducer (NFT) in HAMR. We included the electromagnetic (EM) field analysis in the modeling and considered the back-heating from the media to the head with various heat transfer mechanisms. The results showed that the overcoat layer of the NFT plays an important role for protecting the NFT from high temperature. Degradation of the overcoat layer may result in the early failure of the NFT.

Two Carrier Heat Transfer Modeling for Heat Assisted Magnetic Recording

2013 ◽  
Author(s):  
Neil Zuckerman ◽  
Jin Fang
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Magnetic Recording ◽  
High Energy ◽  
Hot Electrons ◽  
Nanometer Scale ◽  
Phonon Coupling ◽  
Heat Assisted Magnetic Recording ◽  
Carrier Model ◽  
Electron Phonon Coupling

In this work we show the structure and application of a two carrier thermal model applied to a near field transducer, representative of that used in Heat Assisted Magnetic Recording (HAMR). As part of the HAMR device operation, high energy non-thermalized electrons are initially excited by laser incidence on a gold nanostructure. The high energy electrons can travel in a ballistic fashion over longer distances than the optical thickness of gold, resulting in a spreading of the local heat. During their travel the hot electrons collide with lower-energy electrons, thermalizing the hot electrons via inelastic scattering. The thermalized electrons then transfer energy to the lattice due to electron-phonon coupling, as captured in the two carrier model. Starting with an electromagnetic solution for local heating in a sub-micron-scale microfabricated gold structure, the chosen modeling technique applies physical effects of unique interest at the nanometer scale, including brief ballistic transport of hot electrons, experimentally-verified interface thermal resistance, and electron-phonon temperature mismatch. By design, the model is built to use far-field boundary conditions from conventional one-carrier FEMs as well as lubrication-flow computational fluid dynamics. The fundamental governing equations of the two carrier model are two versions of Poisson’s Equation for heat diffusion, coupled by empirically determined terms. These equations are combined with equations for interfacial discontinuities in the temperature fields, yielding a third degree of freedom. The continuous fields are discretized using the finite difference method, and solved using algorithms developed for linear algebra, such as Gaussian Elimination, or non-direct iterative methods. Through use of the model we explore effects of ballistic electron transport length, electron-phonon coupling, as well as interfacial thermal resistance between gold and neighboring ceramics. The model results show the relative impact of the nanoscale heat transfer phenomena in a nanometer scale metal-ceramic structure, allowing us to identify the relative importance of design features and compare candidate designs.

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