Numerical and Experimental Investigation of Nanoscale Heat Transfer in the Head-Media Interface During Static Touchdown

2019 ◽  
Author(s):  
Siddhesh V. Sakhalkar ◽  
Qilong Cheng ◽  
Yuan Ma ◽  
Amin Ghafari ◽  
David B. Bogy
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Magnetic Recording ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Nanoscale Heat Transfer ◽  
Fly Height ◽  
Head Temperature

Abstract With minimum fly height of less than 10 nm in contemporary hard-disk drives, understanding nanoscale heat transfer at the head-media interface is crucial for developing reliable head and media designs. Particularly, with the emergence of Heat-Assisted Magnetic Recording (HAMR) and Microwave-Assisted Magnetic Recording (MAMR), head failure due to overheating has become an increasing concern. There is a need to develop a methodology to use theoretical curves for spacing-dependent nanoscale heat transfer coefficient to predict head and media temperatures in actual hard disk drives. In this study, we present a numerical model to simulate the head and media temperature profiles during static touchdown and compare our results with experiments performed with a magnetic head on a silicon wafer. As the head approaches touchdown with increasing TFC power, the phonon conduction heat transfer coefficient between the head and the substrate increases exponentially, causing a drop in the head temperature vs TFC power curve. Our model shows that the introduction of van der Waals forces between the head and the substrate causes a steeper drop in the head temperature curve and ensures a good quantitative match with experimental results.

Numerical and Experimental Investigation of Nanoscale Heat Transfer Between a Flying Head Over a Rotating Disk

2020 ◽  
Author(s):  
Siddhesh V. Sakhalkar ◽  
Qilong Cheng ◽  
David B. Bogy
Keyword(s):  
Heat Transfer ◽  
Magnetic Recording ◽  
Adhesion Force ◽  
Hard Disk Drives ◽  
Rotating Disk ◽  
Recording Head ◽  
Disk Interface ◽  
Nanoscale Heat Transfer ◽  
Magnetic Recording Head ◽  
Fly Height

Abstract With the minimum fly height less than 10 nm in contemporary hard-disk drives, understanding nanoscale heat transfer at the head-disk interface (HDI) is crucial for developing reliable head and media designs. While flying at near-contact, the fly height and spacing dependent nanoscale heat transfer are significantly affected by interfacial forces in the HDI (such as adhesion force, contact force etc.). Moreover, with the emergence of technologies such as Heat-Assisted Magnetic Recording and Microwave-Assisted Magnetic Recording, head failure due to overheating has become an increasing concern. In this study, we present a numerical model to simulate the head temperature profile and the head-disk spacing for a flying head over a spinning disk and compare our results with touchdown experiments performed with a magnetic recording head flying over a rotating Al-Mg disk. In order to accurately predict the fly height and heat transfer at near-contact, we incorporate asperity based adhesion and contact models, air & phonon conduction heat transfer, friction heating and the effect of disk temperature rise in our model. Our results show that the incorporation of adhesion force between the head and the disk causes a reduction in the fly height, leading to a smaller touchdown power than the simulation without adhesion force.

Capacity Advantage of Array-Reader-Based Magnetic Recording (ARMR) for Next Generation Hard Disk Drives

2014 ◽  
Vol 50 (3) ◽  
pp. 155-161 ◽  
Author(s):  
George Mathew ◽  
Euiseok Hwang ◽  
Jongseung Park ◽  
Glen Garfunkel ◽  
David Hu
Keyword(s):  
Magnetic Recording ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Next Generation

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.

Extendibility of traditional perpendicular magnetic recording for hard disk drives

2011 ◽  
Vol 109 (7) ◽  
pp. 07B774
Author(s):  
James A. Bain ◽  
B. V. K. Vijaya Kumar ◽  
Yu Cai ◽  
Seungjune Jeon ◽  
Ken Mai ◽  
...  
Keyword(s):  
Magnetic Recording ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Perpendicular Magnetic Recording

scholarly journals Ultrahigh-Density Recording Technologies

MRS Bulletin ◽  
1996 ◽  
Vol 21 (9) ◽  
pp. 17-22 ◽  
Author(s):  
Mark H. Kryder
Keyword(s):  
Data Storage ◽  
Magnetic Recording ◽  
Computer Systems ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Time Frame ◽  
Optical Recording ◽  
Disk Drives ◽  
Slowing Down ◽  
Long Term Storage

Magnetic recording and optical recording are the major technologies used to provide long-term storage of information in today's computer systems. Magnetic recording has been used for data storage in computer systems for over 40 years, and the advances in technology that have occurred in that time frame are nothing short of phenomenal. One might expect that after 40 years of dominance, the rate of progress in magnetic recording would be slowing down and that other technologies would be moving in to replace it. However rather than slowing down its rate of progress, magnetic recording is now advancing at a faster rate than at any time in the past. Magnetic hard-disk drives represent the largest segment of the data-storage business, and the number of hard-disk drives sold is increasing at about 20% per year. Tape drives continue to enjoy a very substantial market and are also advancing at a rapid pace while flexible disk drives continue to appear in every personal computer sold and have recently increased capacity by nearly two orders of magnitude.Optical recording was introduced into the marketplace in 1989 and has secured a significant market. However thus far, optical recording has primarily found new market niches, rather than being directly competitive with magnetic recording. CD-ROMs are widely used for the distribution of prerecorded information—a business that is now comparable in size to the magnetic-tape-drive business. On the other hand, erasable, optical drives, which were first introduced in 1989, have not had nearly as much success and have much smaller markets than either magnetic hard drives or tape drives.

Experimental Investigation of Heat Flux at the Head-Disk Interface in Hard Disk Drives

2016 ◽  
Author(s):  
Yuan Ma ◽  
David B. Bogy
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Strong Increase ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Contact Points ◽  
Phonon Conduction

In hard disk drives (HDDs), Thermal Fly-Height Control (TFC) is used to control the head disk spacing for reading or writing data. In order to monitor the spacing and detect possible contacts between the head and disk, a resistive temperature sensor, called Touch-Down Sensor (TDS), is embedded in the slider near potential contact points of the slider against the disk. Understanding the mechanisms of heat transfer across the head-disk interface (HDI) is of major importance, because it is closely related to the design of HDDs, including lubricant flow and contact issues, especially for Heat Assisted Magnetic Recording (HAMR) drives. In this paper, we conducted a series of experiments both on rotating and on non-rotating disks with TDS to find the cause of head temperature change and to validate the heat transfer theory based on phonon conduction. From the experiment, it is shown that air bearing cooling is not responsible for the cooling that occurs in the last nanometer before contact. Based on phonon conduction predictions, we should expect a decrease in slope of the non-contact curve as the spacing becomes less than 1 or 2 nm because of the strong increase in the heat flux due to phono conduction in this range.

Thermal Lagging of Multilayered Structure in Heat-Assisted Magnetic Recording Systems

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Jian Su ◽  
Tingting Tang ◽  
Ruixin Lu ◽  
Peng Yu
Keyword(s):  
Temperature Gradient ◽  
Thermal Resistance ◽  
Magnetic Recording ◽  
Heat Sink ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Interfacial Thermal Resistance ◽  
Disk Drives ◽  
Horizontal Temperature Gradient ◽  
Heat Assisted Magnetic Recording

Abstract In the present study, we numerically investigate the thermal lagging behavior on the hard disk drives in heat-assisted magnetic recording systems via the optical absorption model. The influences of overcoats, laser radius, relative scanning speed, interfacial thermal resistance, and the heat sink layer on the thermal lagging behavior are studied in detail. It is found that the thermal lagging distance, i.e., the horizontal distance between the location of the maximum temperature and the laser center, increases with an increment of speed and/or radius of the laser spot. The overcoats, the interfacial thermal resistance, and the heat sink layer have negligible effects on the lagging distance. Thus, the multilayered disk can be simplified as a single-layer disk for investigating thermal lagging distance. Meanwhile, the horizontal temperature gradient varies with these factors. Different overcoats result in different horizontal temperature gradient owing to the difference of in-plane thermal diffusivity. A laser with a smaller radius or a slower speed leads to a higher horizontal temperature gradient. The thermal resistance influences the horizontal temperature gradient insignificantly. This study may provide useful information for the design of hard disk drives for heat-assisted magnetic recording technologies.

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