Diamond-like carbon (DLC) is a metastable form of amorphous carbon with significant sp3 bonding. DLC is a semiconductor with a high mechanical hardness, chemical inertness, and optical transparency. This review will describe the deposition methods, deposition mechanisms, characterisation methods, electronic structure, gap states, defects, doping, luminescence, field emission, mechanical properties and some applications of DLCs. The films have widespread applications as protective coatings in areas, such as magnetic storage disks, optical windows and micro-electromechanical devices (MEMs).

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Diamond-like amorphous carbon

The unprecedented ability of nanometallic (that is, plasmonic) structures to concentrate light into deep-subwavelength volumes has propelled their use in a vast array of nanophotonics technologies and research endeavours. Plasmonic light concentrators can elegantly interface diffraction-limited dielectric optical components with nanophotonic structures. Passive and active plasmonic devices provide new pathways to generate, guide, modulate and detect light with structures that are similar in size to state-of-the-art electronic devices. With the ability to produce highly confined optical fields, the conventional rules for light-matter interactions need to be re-examined, and researchers are venturing into new regimes of optical physics. In this review we will discuss the basic concepts behind plasmonics-enabled light concentration and manipulation, make an attempt to capture the wide range of activities and excitement in this area, and speculate on possible future directions.

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Plasmonics for extreme light concentration and manipulation.

Singular Integral Equations. By N.I. Muskhelishvili. Translated fromthe 2nd Russian edition by J.R.M. Radok. Pp. 447. F1. 28.50. 1953. (Noordhoff, Groningen)

Our aim is to propose a theory which goes beyond the classical formulation of thermodynamics. This is achieved by enlarging the space of basic independent variables, through the introduction of non-equilibrium variables, such as the dissipative fluxes appearing in the balance equations. The next step is to find evolution equations for the dissipative fluxes. Whereas the evolution equations for the classical variables are given by the usual balance laws, no general criteria exist concerning the evolution equations of the dissipative fluxes, with the exception of the restrictions imposed on them by the second law of thermodynamics.

https://iopscience.iop.org/article/10.1088/0034-4885/51/8/002/pdf

Extended irreversible thermodynamics

Surface-tension-driven flows and, in particular, their tendency to decay spontaneously into drops have long fascinated naturalists, the earliest systematic experiments dating back to the beginning of the 19th century. Linear stability theory governs the onset of breakup and was developed by Rayleigh, Plateau, and Maxwell. However, only recently has attention turned to the nonlinear behavior in the vicinity of the singular point where a drop separates. The increased attention is due to a number of recent and increasingly refined experiments, as well as to a host of technological applications, ranging from printing to mixing and fiber spinning. The description of drop separation becomes possible because jet motion turns out to be effectively governed by one-dimensional equations, which still contain most of the richness of the original dynamics. In addition, an attraction for physicists lies in the fact that the separation singularity is governed by universal scaling laws, which constitute an asymptotic solution of the Navier-Stokes equation before and after breakup. The Navier-Stokes equation is thus continued uniquely through the singularity. At high viscosities, a series of noise-driven instabilities has been observed, which are a nested superposition of singularities of the same universal form. At low viscosities, there is rich scaling behavior in addition to aesthetically pleasing breakup patterns driven by capillary waves. The author reviews the theoretical development of this field alongside recent experimental work, and outlines unsolved problems.

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Nonlinear dynamics and breakup of free-surface flows

Particle contamination in a cavity, or a recessed region, on the slider surface is an important issue in slider designs for magnetic recording. In this paper, a model is developed for the simulation of particle motion in a recessed region, in which various forces such as viscous drag, Saffman lift, Magnus lift, and gravity are considered. It is found that the latter two forces have a very small effect on the vertical motion of the particles compared with the Saffman lift, and they can be neglected in the analysis. It is also found, through the simulation for various cases, that the Saffman lift is not so important for the motion of the smaller particles (d<100 nm) as for the motion of larger particles, and that the magnitude of the velocity of particles relative to the air flow affects the Saffman lift, or vertical motion of the particles, significantly. The air flow velocity is relatively low in a recessed region, and a particle often has a large relative velocity with positive sign when entering it, whi...

Effects of lift on the motion of particles in the recessed regions of a slider

Al/sub 2/O/sub 3/TiC sliders used in magnetic recording hard disk drives were coated with diamond-like carbon (DLC) to improve the wear durability of the head-disk interface (HDI). Both contact-start-stop and constant speed drag tests were conducted during which the build up of friction associated with wear of the thin film disks was measured in a standard disk wear tester. The friction values increased three or fourfold in the tests with uncoated sliders, whereas tests conducted with DLC coated sliders showed only a twofold increase in friction in the early part of the test followed by constant friction values afterwards. This major improvement was found for as little as 7 nm of coating on the sliders. Increases of wear durability of the head-disk interface by factors of 50-200 were obtained. >

Enhancement of head-disk interface durability by use of diamond-like carbon overcoats on the slider's rails

A numerical comparison of one-dimensional fluid jet models applied to drop-on-demand printing

Negative pressure sliders also have many merit features, but they can develop an undesirable suction force during dynamic unload. In this paper the dynamics of negative pressure sliders during the unload process was investigated by simulation and experiment. A simplified L/UL model for the suspension system was created, and an experimental setup was built to directly measure the air bearing forces. Two slider designs have been simulated and measured at various disk rotation speeds. Good correlation between the experimental and simulation results was achieved. During unload the air bearing suction force causes dimple separation. By selecting an optimal speed for unload, we can decrease the amount of dimple separation for a given slider design.

Dynamics of the unload process for negative pressure sliders

As the head-disk spacing reduces in order to achieve the areal density goal of 1 Tb/in.2 , dynamic stability of the slider is compromised due to a variety of proximity interactions. Lubricant pickup by the slider from the disk is one of the major reasons for decrease in the stability as it contributes to meniscus forces and contamination. Disk-to-head lubricant transfer leads to lubricant pickup on the slider and also causes depletion of lubricant on the disk. In this paper we experimentally and numerically investigate the process of disk-to-head lubricant transfer using a half-delubed disk, and we propose a parametric model based on the experimental results. We also investigate the dependence of disk-to-head lubricant transfer on the disk lubricant thickness, lubricant type and the slider ABS design. It is concluded that disk-to-head lubricant transfer occurs without slider-disk contact and there can be more than one timescale associated with the transfer. Further, the transfer increases non-linearly with increasing disk lubricant thickness. Also, it is seen that the transfer depends on the type of lubricant used, and is less for Ztetraol than for Zdol. The slider ABS design also plays an important role, and a few suggestions are made to improve the ABS design for better lubricant performance.Copyright © 2006 by ASME

David B. Bogy

Papers

Effects of lift on the motion of particles in the recessed regions of a slider

Enhancement of head-disk interface durability by use of diamond-like carbon overcoats on the slider's rails

A numerical comparison of one-dimensional fluid jet models applied to drop-on-demand printing

Dynamics of the unload process for negative pressure sliders

Lubricant Depletion and Disk-to-Head Lubricant Transfer at the Head-Disk Interface in Hard Disk Drives