Experimental Study of Lubricant Depletion in Heat Assisted Magnetic Recording

S., Y.; Chen, X. Y.; Zhao, Jingming; Yu, Shengkai; Liu, B.; Seet, H.L.; Ng, Kwai-Kong; Hu, Jingtian; Shi, J.Z.

doi:10.1109/tmag.2011.2170962

Cited by 17 publications

(5 citation statements)

References 4 publications

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“…Lubricant reflow has not been required of PMR media thus far. Several papers report on the experimental reflow kinetics following laser irradiation [2,16]. For example, approximately 24 hr was needed to recover a 12 Å Z-Tetraol trough having a 65 µm diameter [2].…”

Section: Introductionmentioning

confidence: 99%

Z-Tetraol Reflow in Heat-Assisted Magnetic Recording

Waltman

2016

Tribology Online

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Lubricant reflow for Z-Tetraol is characterized for heat-assisted magnetic recording (HAMR). The thickness-dependent diffusion constant, D(h), is determined from flow experiments for submonolayer Z-Tetraol films between 2.5 and 13 Å. Fickian diffusion using experimental D(h) values are used to numerically simulate lubricant reflow into HAMR laser-depleted troughs as a function of trough number, trough depth, trough distance and trough width. Reflow is computed to be slower for multiple, wider and deeper troughs. Reflow kinetics as a function of trough separation distance is complicated by adjacent trough interactions. Two major kinetic regimes are identified. Multiple troughs that have not coalesced recover more quickly. Once multiple troughs coalesce into a single larger trough, reflow kinetics is drastically slowed. The crossover time between the two kinetic regimes is computed to be approximately 400 millisec for the system under investigation here, but will be a strong function of trough number, width, depth and separation distances. The simulation of multiple troughs provides significant insight into HAMR conditions. Single trough lubricant studies may be misleading for HAMR systems.

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Section: Introductionmentioning

confidence: 99%

Z-Tetraol Reflow in Heat-Assisted Magnetic Recording

Waltman

2016

Tribology Online

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“…Thus far, most experimental HAMR laser irradiations have been conducted in the ~ 10 µm (10,000 nm) range so HAMR-realistic length scales have not yet been experimentally approached. Many studies report as much as several Å of lubricant film thickness lost depending upon laser power and exposure time [13][14][15][16][17]. Our own experimental spin-stand studies using HAMR prototype heads indicate a combined lubricant/carbon film thickness loss of approximately 2-4 Å after 10 6 cycles near the Curie temperature of the media.…”

Section: Simulation Methodsmentioning

confidence: 80%

Duty Cycle Effects in Z-Tetraol Reflow in Heat-Assisted Magnetic Recording

Waltman

2016

Tribology Online

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Lubricant reflow for 10 Å Z-Tetraol film is characterized for heat-assisted magnetic recording by numerical simulation using the experimentally determined thickness-dependent diffusion equation. The competition between laser-induced lubricant depletion (troughs) and subsequent healing by reflow is investigated as a function of lubricant depletion rate, trough width, trough depth, and duty cycle (reflow time between successive laser exposures). The simulations include 1, 5, 9 and 13 adjacent troughs. Trough width of 50 nm with an edge-to-edge separation distance of 50 nm and laser depletion rates of 1.0, 0.1 and 0.001 Å/cycle are simulated. Reflow kinetics on 13 troughs with a trough width of 20 nm and an edge-to-edge separation distance of 20 nm is also included to probe the effects in the limit of very small laser spots. Duty cycles of 10 and 100 millisec are used in the simulations. The results of the numerical simulations indicate that trough recovery by reflow increases with increasing duty cycle or decreasing number of adjacent troughs, trough separation distance and laser depletion rate. Conclusions based upon single trough studies are misleading for HAMR interfaces.

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“…Ma et al [13] demonstrated that the design of the air-bearing surface plays a significant role in determining lubricant transfer. Ma et al [14] experimentally demonstrated lubricant depletion under laser irradiation by utilizing a self-developed set-up. Wu [15] analyzed the temperature distribution of HAMR (heat-assisted magnetic recording), and based on the results obtained, it was determined that the flow and depletion of the lubricant primarily resulted from two factors: evaporation and thermo-capillary stress.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Slider Configuration on Lubricant Depletion at the Slider/Disk Contact Interface

Chen,

Zhou,

Tang

2024

Lubricants

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With decreasing clearance between the protrusion of a slider and a disk interface, there is a higher likelihood of contact occurring during shock or vibration experienced by hard disk drives (HDDs), which may induce lubricant depletion. Based on the molecular dynamics (MD) model of perfluoropolyether lubricant with a coarse-grained beads spring approach, we compared the slider configurations’ influence on the lubricant transfer volume quantitatively. By further investigating the parameters of the cylindrical asperities, including the width and depth, as well as considering the asperity amounts of the slider, we successfully observed the lubricant depletion process during slider and disk contact. The results demonstrate that the penetration depth was reduced as the asperity amount increased, mainly owing to the increased contact area between the surfaces. The decreasing depth of the asperity and the increasing width of the asperity helped to reduce the depletion volume. In addition, the utilization of a cylindrical slider configuration can contribute to a reduction in lubricant depletion resulting from contact between the head and disk.

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Experimental Study of Lubricant Depletion in Heat Assisted Magnetic Recording

Cited by 17 publications

References 4 publications

Z-Tetraol Reflow in Heat-Assisted Magnetic Recording

Z-Tetraol Reflow in Heat-Assisted Magnetic Recording

Duty Cycle Effects in Z-Tetraol Reflow in Heat-Assisted Magnetic Recording

The Effect of Slider Configuration on Lubricant Depletion at the Slider/Disk Contact Interface

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