Thermal decomposition and desorption of PFPE Zdol on a DLC substrate using quartic bond interaction potential

In heat assisted magnetic recording (HAMR) system, heating of the hard disk magnetic layer is carried out by applying laser rays during the movement of the read/write head over the carbon overcoat for the purpose of reading and writing on its magnetic layer.

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The Dependence of the Corrosion Behavior of Rigid Disk Magnetic Recording Media on the Deposition Conditions of the Underlayer, Magnetic Layer, and Carbon Overcoat

Journal of The Electrochemical Society ◽

10.1149/1.2069411 ◽

1992 ◽

Vol 139 (5) ◽

pp. 1352-1358 ◽

Cited By ~ 9

Author(s):

Paul J. Sides

Keyword(s):

Corrosion Behavior ◽

Magnetic Recording ◽

Magnetic Layer ◽

Recording Media ◽

Magnetic Recording Media ◽

Carbon Overcoat ◽

Rigid Disk ◽

Deposition Conditions

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Reactive Molecular Dynamics Study of Thermal Decomposition and Transfer of Perfluoropolyether Lubricant in Heat-assisted Magnetic Recording

The Proceedings of Mechanical Engineering Congress Japan ◽

10.1299/jsmemecj.2020.s16102 ◽

2020 ◽

Vol 2020 (0) ◽

pp. S16102

Author(s):

Xingyu CHEN ◽

Hedong ZHANG ◽

Kenji FUKUZAWA ◽

Shintaro ITOH ◽

Naoki AZUMA

Keyword(s):

Molecular Dynamics ◽

Thermal Decomposition ◽

Magnetic Recording ◽

Heat Assisted Magnetic Recording ◽

Reactive Molecular Dynamics ◽

Perfluoropolyether Lubricant

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Air Bearing Pushback in Heat Assisted Magnetic Recording

ASME 2019 28th Conference on Information Storage and Processing Systems ◽

10.1115/isps2019-7503 ◽

2019 ◽

Author(s):

Shaomin Xiong ◽

Robert Smith ◽

Chanh Nguyen ◽

Youfeng Zhang ◽

Yeoungchin Yoon

Keyword(s):

Magnetic Recording ◽

Hard Disk Drives ◽

Hard Disk ◽

Disk Drive ◽

Flying Height ◽

Air Bearing ◽

Magnetic Media ◽

Heat Assisted Magnetic Recording ◽

Height Control ◽

Different Dimensions

Abstract The air bearing surface is critical to the spacing control in current hard disk drives (HDDs). Thermal protrusions, including thermal flying height control (TFC) and writer coil protrusion, drive the reader/writer elements closer to the magnetic media. The spacing control actuation efficiency depends on the air bearing push back response after the TFC or writer protrudes. In the next generation hard disk drive technology, heat assisted magnetic recording (HAMR), laser induced protrusions further complicate the spacing control. The laser induced protrusions, such as the localized NFT protrusion and a wider change of the crown and camber, have very different dimensions and transient characteristics than the traditional TFC and writer protrusion. The dimension of the NFT protrusion is relatively smaller, and the transient is much faster than the TFC protrusion. However, it is found that the NFT protrusion is large enough to generate an air bearing push back effect, which changes the read and write spacing when the laser is powered on. To accurately control spacing in HAMR, this push back effect has to be taken into account.

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Experimental Study on Laser-Induced Protrusion in Heat-Assisted Magnetic Recording

ASME 2020 29th Conference on Information Storage and Processing Systems ◽

10.1115/isps2020-1903 ◽

2020 ◽

Author(s):

Qilong Cheng ◽

Haoyu Wang ◽

Siddhesh V. Sakhalkar ◽

David B. Bogy

Keyword(s):

Magnetic Recording ◽

Laser Heating ◽

Hot Spot ◽

Magnetic Layer ◽

Optical Power ◽

Linear Velocity ◽

Component Level ◽

Heat Assisted Magnetic Recording ◽

Power Change ◽

The Media

Abstract In heat-assisted magnetic recording (HAMR), a laser is introduced to create a hot spot on the media and locally heat the magnetic layer to its Curie temperature. Besides the optical power that the laser provides to the media, thermal energy diffuses inside the slider and induces an extra protrusion, which is called laser-induced protrusion (LIP). The LIP needs to be considered and compensated during flying in the HAMR conditions. In this study, we focus on long timescale (milliseconds) of laser heating during the flying condition. When the laser is switched from OFF to ON, the touchdown power, indicated by an acoustic emission (AE) sensor, decreases due to spacing loss and the touchdown power change (ΔTDP) is used as the measure of the LIP. A component-level spinstand stage for HAMR heads and media is used to study the LIP as a function of laser-on time, laser current and linear velocity. Our experimental results show that it takes around 20 ms for the LIP to reach steady state and the protrusion size is proportional to the square of laser current. As the operating linear velocity increases from 12 m/s to 24 m/s, the LIP decreases by approximately 52%.

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Laser-Heating-Induced Damage to Ultrathin Carbon Overcoat in Heat-Assisted Magnetic Recording

Tribology Letters ◽

10.1007/s11249-013-0268-x ◽

2013 ◽

Vol 53 (1) ◽

pp. 303-310 ◽

Cited By ~ 10

Author(s):

Y. S. Ma ◽

Y. J. Man ◽

M. Shakerzadeh ◽

H. L. Seet ◽

R. Ji ◽

...

Keyword(s):

Magnetic Recording ◽

Laser Heating ◽

Carbon Overcoat ◽

Heat Assisted Magnetic Recording

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Stress Induced Permanent Magnetic Signal Degradation of Perpendicular Magnetic Recording System

Journal of Tribology ◽

10.1115/1.2991123 ◽

2008 ◽

Vol 131 (1) ◽

Cited By ~ 14

Author(s):

Sung-Chang Lee ◽

Soo-Youl Hong ◽

Na-Young Kim ◽

Joerg Ferber ◽

Xiadong Che ◽

...

Keyword(s):

Magnetic Recording ◽

Hard Disk Drives ◽

Magnetic Layer ◽

Mechanical Damage ◽

Hard Disk ◽

Disk Drive ◽

Magnetic Signal ◽

Perpendicular Magnetic Recording ◽

Signal Degradation ◽

The Media

Model scratches of the size found in hard disk drives are produced under controlled conditions at a series of applied loads on both longitudinal magnetic recording (LMR) media and perpendicular magnetic recording (PMR) media using a diamond tip. The scratches are created at low speed, eliminating thermal considerations from the interpretation of the media response. Nanoindentations are produced as well. The scratches and indentations are characterized by atomic force microscope (AFM), magnetic force microscope (MFM), and also by the same magnetic reader and writer used in an integrated hard disk drive (HDD). A comparison of the response of PMR and LMR media shows the PMR media to have larger scratches and greater magnetic signal degradation than LMR media for a given scratch load. The extent of magnetic damage, as measured by MFM, is greater than the extent of surface mechanical damage, as measured by AFM. Analysis of scratches using the HDD reveals that the magnetic damage is irreversible and permanent damage in magnetic layer, which is confirmed by cross section transmission electron microscope image. The experiments reveal the mechanism for magnetic scratch erasure in the absence of thermal effects. This understanding is expected to lead to improved designs for mechanical scratch robustness of next-generation PMR media.

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Carbon Overcoat Oxidation in Heat-Assisted Magnetic Recording

IEEE Transactions on Magnetics ◽

10.1109/tmag.2012.2236645 ◽

2013 ◽

Vol 49 (7) ◽

pp. 3721-3724 ◽

Cited By ~ 34

Author(s):

B. K. Pathem ◽

X.-C. Guo ◽

F. Rose ◽

N. Wang ◽

K. Komvopoulos ◽

...

Keyword(s):

Magnetic Recording ◽

Carbon Overcoat ◽

Heat Assisted Magnetic Recording

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

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4046022 ◽

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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