Impact of Pattern Media Topography on the Tribology of Head-Disk Interfaces

Bit patterned media (BPM) is being pursued by the disk drive industry as a way of extending magnetic recording densities beyond 1 Tbits/in2 [1]. As the patterned topography of an unplanarized BPM disk generates a tribology quite different than smooth, continuous media, it is important to assess how this topography will impact the tribology of head-disk interfaces (HDI). In this paper, we quantify the impact of BPM topography on flying height modulation.

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Impact of Touchdown Detection on Bit Patterned Media Robustness

ASME 2013 Conference on Information Storage and Processing Systems ◽

10.1115/isps2013-2871 ◽

2013 ◽

Author(s):

Jia-Yang Juang ◽

Kuan-Te Lin

Keyword(s):

Areal Density ◽

Flying Height ◽

Head Disk Interface ◽

Bit Patterned Media ◽

Patterned Media ◽

Disk Interface ◽

Recording Process ◽

Friction Temperature ◽

The Media ◽

The Impact

Bit patterned media (BPM) is considered as a revolutionary technology to enable further increase of areal density of magnetic recording beyond 1 Tbits/in2 [1]. Implementing BPM technology, however, significantly increases the complexity of the recording process, but also poses tremendous tribological challenges on the head-disk interface (HDI) [2]. One of the major challenges facing BPM is touchdown detection by thermal flying-height control (TFC), in which a minute heater located near the read/write transducers is used to thermally protrude a small portion of the slider into contact with the disk, and the contact is then detected by directly or indirectly measuring the friction, temperature rise or vibration caused by the contact [3]–[7]. Most recording heads rely on touchdown detection to achieve a desired flying height (FH), which approaches sub-1-nm regime for many of today’s commercial drives. As a result sensitive and accurate touchdown detection is of critical importance for a reliable head-disk interface by reducing contact duration and unnecessary interaction between the slider and the disk. However, the impact of touchdown on the mechanical robustness of the media has not been properly studied.

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The Influence of Temperature and Humidity on the ABS Contaminations

2014 Conference on Information Storage and Processing Systems ◽

10.1115/isps2014-6981 ◽

2014 ◽

Cited By ~ 2

Author(s):

Fuhao Cui ◽

Jinhong Hu ◽

Yue Peng ◽

Hui Li ◽

Shengnan Shen ◽

...

Keyword(s):

Shear Stress ◽

Flow Pattern ◽

Air Flow ◽

Disk Drive ◽

Flying Height ◽

Flow Shear ◽

Slip Boundary ◽

Temperature And Humidity ◽

Flow Shear Stress ◽

The Impact

In order to increase the areal recording density of hard disk drive beyond 1 Tb/in2, the flying height has to be reduced to several nanometers. At such a low flying height, particles and lube contaminations, which could lead to a transient vibration and flying height modulation in a hard disk drive, are becoming more and more serious. In this work, it studies the influence of temperature and humidity on the air flow pattern, velocity and shear stress distribution on the air bearing surface (ABS) of slider using a self-developed simulator. It first solves the generalized steady state Reynolds equation with slip boundary conditions. Then it solves the reduced Navier-Stokes (N-S) equation with slip boundary conditions to get the air velocity distribution, i.e., identify the air flow pattern on the ABS. The stagnation lines and areas of air flow are calculated to judge the contamination area. On the other hand, it calculates the air shear stress distribution on the ABS since the air shear stress is the main driving force for the lubricant and particles migration and contaminations. After that, the impact of the temperature and humidity on the air flow pattern is analyzed by applying the Sutherland equation and mixed gas viscosity calculation equation. The simulation results indicate that the impact of temperature and humidity on the air flow pattern is un-conspicuous. However, the peak velocity of the air flow, which contains no vapor, reduces almost 10%, and the peak air flow shear stress increases less than 1.5%, with the increase of operational temperature from 298.15 K to 343.15 K. In addition, the peak velocity of the air flow increasing almost 4%, and the peak air flow shear stress keeps almost same, with the increase of the operational mole fraction of vapor from 5% to 15%.

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Concatenated Coding Schemes for High Areal Density Bit-Patterned Media Magnetic Recording

IEEE Transactions on Magnetics ◽

10.1109/tmag.2017.2746339 ◽

2018 ◽

Vol 54 (2) ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Hidetoshi Saito

Keyword(s):

Magnetic Recording ◽

Areal Density ◽

Concatenated Coding ◽

Bit Patterned Media ◽

Patterned Media ◽

Coding Schemes

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Nanopatterned L10-FePt nanoparticles from single-source metallopolymer precursors for potential application in ferromagnetic bit-patterned media magnetic recording

Polymer Chemistry ◽

10.1039/c6py00714g ◽

2016 ◽

Vol 7 (27) ◽

pp. 4467-4475 ◽

Cited By ~ 27

Author(s):

Zhengong Meng ◽

Guijun Li ◽

Sheung-Mei Ng ◽

Hon-Fai Wong ◽

Sze-Chun Yiu ◽

...

Keyword(s):

High Throughput ◽

Magnetic Recording ◽

Potential Application ◽

Nanoimprint Lithography ◽

Fept Nanoparticles ◽

Single Source ◽

Bit Patterned Media ◽

Patterned Media

A new single-source metallopolymer precursor P was applied for the synthesis of magnetic FePt nanoparticles, which was also suitable for patterning by high-throughput nanoimprint lithography to obtain ferromagnetic nanolines.

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Micromagnetic Simulation of L10-FePt-Based Exchange-Coupled-Composite-Bit-Patterned Media with Microwave-Assisted Magnetic Recording at Ultrahigh Areal Density

Micromachines ◽

10.3390/mi12101264 ◽

2021 ◽

Vol 12 (10) ◽

pp. 1264

Author(s):

Pirat Khunkitti ◽

Naruemon Wannawong ◽

Chavakon Jongjaihan ◽

Apirat Siritaratiwat ◽

Anan Kruesubthaworn ◽

...

Keyword(s):

Magnetic Recording ◽

Magnetic Domain ◽

Hysteresis Loops ◽

Areal Density ◽

Bit Patterned Media ◽

Patterned Media ◽

Microwave Assisted ◽

The Media ◽

5 Ghz ◽

Exchange Coupled Composite

In this work, we propose exchange-coupled-composite-bit-patterned media (ECC-BPM) with microwave-assisted magnetic recording (MAMR) to improve the writability of the magnetic media at a 4 Tb/in2 recording density. The suitable values of the applied microwave field’s frequency and the exchange coupling between magnetic dots, Adot, of the proposed media were evaluated. It was found that the magnitude of the switching field, Hsw, of the bilayer ECC-BPM is significantly lower than that of a conventional BPM. Additionally, using the MAMR enables further reduction of Hsw of the ECC-BPM. The suitable frequency of the applied microwave field for the proposed media is 5 GHz. The dependence of Adot on the Hsw was additionally examined, showing that the Adot of 0.14 pJ/m is the most suitable value for the proposed bilayer ECC-BPM. The physical explanation of the Hsw of the media under a variation of MAMR and Adot was given. Hysteresis loops and the magnetic domain of the media were characterized to provide further details on the results. The lowest Hsw found in our proposed media is 12.2 kOe, achieved by the bilayer ECC-BPM with an Adot of 0.14 pJ/m using a 5 GHz MAMR.

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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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