David Bogy

University of California, Berkeley | UCB

In this protocol, we present a facile nanoscale thermal mapping technique for electronic devices by use of atomic force microscopy and a phase change material Ge2Sb2Te5. We describe steps for Ge2Sb2Te5 thin film coating, Ge2Sb2Te5 temperature calibration, thermal mapping by varying heater power, and thermal mapping by varying heating time. The prot...

This report investigates the kinetics of lubricant molecules in the HAMR air bearing to understand the initiation and growth of PFPE contamination on the head surface. The collisions with the air bearing induce three forces—drag, thermophoresis, and lift. Of these, we find that lift forces are negligible. Then, a sensitivity analysis of the remaini...

A main challenge in Heat-Assisted Magnetic Recording technology is the build-up of contaminants called smear on the near field transducer. In this paper, we investigate the role of optical forces originating from the electric field gradient in the formation of smear. First, based on suitable theoretical approximations, we compare this force with ai...

It is demonstrated that the commonly accepted mathematical derivation of the fluctuation-dissipation theorem for electromagnetic fields in spatial domains involves restrictive conditions that essentially limit the applicability of the Theorem to the analysis of large-scale radiative heat transfer, and therefore, it may not be applicable to problems...

Heat-assisted magnetic recording (HAMR), one of the promising hard disk drive technologies to achieve areal density > 10 Tb/in\(^2\), integrates a laser across its head-disk interface to assist data writing. However, the laser brings a disk-to-head material transfer problem due to the temperature difference. The thermally-induced material buildup o...

This work presents a novel study of radiative heat transfer between closely separated plates based on an extension of Planck’s spectrum of thermal radiations to systems with a steady heat flux. This extension together with electromagnetic wave theory is chosen specifically to avoid the commonly used so-called fluctuation dissipation theory, which i...

Heat assisted magnetic recording, as one of the next generation hard disk drive solutions to high areal density over 1 Tb/in. ² , integrates a laser delivery system to facilitate data writing. A laser beam is launched from the recording head and is focused on the recording disk to locally heat the disk (400–500 °C), which is even hotter than the he...

In hard disk drives, a recording head and a recording disk constitute a high-speed sliding system: head–disk interface, where the head with a prescribed thermal protrusion on its surface flies over the rotating disk at an air gap < 1–2 nm. Currently, the magnetic recording operations involve two embedded joule heaters in the recording head to gener...

The head-disk interface (HDI) in heat-assisted magnetic recording (HAMR) hard disk drives is a system where a laser beam is launched from a recording head and focused on a recording disk to facilitate data writing. During the laser exposure, material transfers from the disk to the head surface due to the high temperature field and steep thermal gra...

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...

The microelectronics industry is pushing the fundamental limit on the physical size of individual elements to produce faster and more powerful integrated chips. These chips have nanoscale features that dissipate power resulting in nanoscale hotspots leading to device failures. To understand the reliability impact of the hotspots, the device needs t...

By measuring the touchdown power change, researchers study the spacing loss and extract the angstrom-level protrusion. To increase data density and smaller bit size on magnetic storage devices such as hard drives, the material's coercivity must be high enough to protect the data from unwanted magnetic disturbances. However, a high coercivity would...

In heat-assisted magnetic recording (HAMR), a laser is employed above the read-write transducer to provide energy to the media, lowering its coercivity. However, the laser also brings thermal energy diffusion inside the slider and induces an extra angstrom-level protrusion, which we call laser induced protrusion (LIP). The LIP needs to be taken int...

A recently understood ability of sound to cross narrow vacuum gaps between material bodies has numerous implications in modern technology, where it opens additional channels for the transfer of heat and acoustic signals between narrowly separated objects. Acoustic vibrations in a body are characterized by perturbations of its surface and of its mat...

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). T...

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...

A recently understood ability of sound to cross narrow vacuum gaps between material bodies has numerous implications in modern technology where it opens additional channels for transfer of heat and acoustic signals between narrowly separated objects. Acoustic vibrations in a body are characterized by perturbations of its surface and of its material...

Radiative heat transfer across nanoscale-thick layers attracts considerable attention because of its importance for modern technology, and also because of the evidence that conventional methods of radiative heat transfer fail at such small scales. This paper analyzes several approaches to this problem that have been proposed since the late 1960s wh...

In hard disk drives (HDD), the head-media spacing has decreased to less than 10 nm. Across this nanoscale gap, the heat transfer between the head and media may affect the air-bearing design, lubricant transfer and contact issues. Thus, understanding the heat transfer mechanism is very important to magnetic recording, especially for Heat Assisted Ma...

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 ov...

One of the challenges in heat-assisted magnetic recording (HAMR) is the formation of write-induced head contamination at the near-field transducer. A possible mechanism that has been proposed for this contamination is the transfer of lubricant from the disk to the head due to temperature driven evaporation/condensation. Most previous studies on lub...

The high-temperature laser heating during heat-assisted magnetic recording (HAMR) causes the media lubricant to deform and transfer to the head via evaporation/condensation. The ability of the lubricant to withstand this writing process and sufficiently recover post-writing is critical for robust read/write performance. Moreover, the media-to-head...

We extend the statistical analysis of equilibrium systems to systems with a constant heat flux. This extension leads to natural generalizations of Maxwell–Boltzmann’s and Planck’s equilibrium energy distributions to energy distributions of systems with a net heat flux. This development provides a long needed foundation for addressing problems of na...

In Heat-Assisted Magnetic Recording (HAMR) technology, the lubricant layer coating on the disk is exposed to severe thermal conditions, leading to evaporation, depletion, and chemical degradation. In general, those studying the effects of laser exposure on lubricant depletion and recovery have assumed the lubricant to be a viscous fluid and have mo...

The heat assisted magnetic recording (HAMR) technology is expected to increase the areal density of the hard disk drives up to 10 Tb/in.² This paper presents a numerical thermal study of near field transducers (NFTs), a key component in HAMR. Both an electromagnetic and a heat transfer model are included. Instead of assuming a heat transfer model a...

The heat management problem in the heat assisted magnetic recording (HAMR) has been a long-term issue. In this paper, we investigated the temperature increase of a “lollipop” type near field transducer (NFT) in HAMR. We included the electromagnetic (EM) field analysis in the modeling and considered the back-heating from the media to the head with v...

Understanding the heat transfer in the head disk interface (HDI) in the heat assisted magnetic recording (HAMR) is important. In this paper, we report on a series of experiments to study the heat transfer in the HDI using the perpendicular magnetic recording (PMR) heads and media. The temperature increase of the embedded contact sensor (ECS) and th...

We develop a theory of thermal transport in nanoscale-layered structures based on wave processes. The theory incorporates two fundamental principles, first, that the spectra of thermally excited waves are determined by the temperature differential and the heat flux, and second, that the wave fields in the heat exchanging domains are coupled. The de...

In the developing heat-assisted magnetic recording technology, a laser heats up the magnetic media to the Curie temperature of a few hundred degrees celsius for a few nanoseconds. Accordingly, the thin-film lubricant coating on the disk experiences thermo-capillary and evaporation effects followed by its depletion. In order to maintain a reliable h...

Maskless nanolithography is an agile and cost effective approach if their throughputs can be scaled for mass production purposes. Using plasmonic nanolithography (PNL) approach, direct pattern writing was successfully demonstrated with around 20 nm half-pitch at high speed. Here, we report our recent efforts of implementing a high-throughput PNL pr...

Nanoscale analysis characterized by microscopy with atomic resolution demand that the targeted surface remains nearly static. Therefore, the interaction between two fast moving surfaces requires a unique methodology to capture its dynamics when contacts are of nominal area on the order of 100 μm2 but only a few angstroms in depth. We present a cont...

We present here a controlled measurement of heat flux across a closing gap that is initially less than 10 nm wide between two solid surfaces at different temperatures. The measured heat transfer is compared with our published theoretical analyses of this phenomenon that show thermal radiation dominates the heat transfer for gaps wider than about 1–...

In this paper, we analyze the radiative heat transport in layered structures. The analysis is based on our prior description of the spectrum of thermally excited waves in systems with a heat flux. The developed method correctly predicts results for all known special cases for both large and closing gaps. Numerical examples demonstrate the applicabi...

Laser heating has been introduced in heat-assisted magnetic recording in order to reduce the magnetic coercivity and enable data writing. However, the heat flow inside a couple of nanometers head-disk gap is still not well understood. An experimental stage was built for studying heat transfer in the head-disk interface (HDI) and the heat-induced in...

In current hard disk drives, the minimum air-bearing clearance is of the order of 1 nm during the read/write process. At this ultra-low spacing, lubricant from the disk often transfers to the slider’s air-bearing surface imposing a significant degradation of its performance. It is necessary to make accurate predictions of the lubricant’s response a...

With the introduction of thermal fly-height control sliders, the local head-disk clearance can be reduced to a range from ∼10 nm to contact. This actively controlled touchdown (TD) has been used as a way to study the head-disk interface (HDI), the characteristics of which greatly affect the areal density and reliability of drives. In this paper, a...

In heat assisted magnetic recording (HAMR) technology for hard disk drives, the media will be heated to about 500 °C during the writing process in order to reduce its magnetic coercivity and thus allow data writing with the magnetic head transducers. The traditional lubricants such as Z-dol and Z-tetraol may not be able to perform in such harsh hea...

In this paper, we analyze the heat transport by acoustic waves in arbitrary layered structures that may include several vacuum layers. The analysis is based on our prior description of the spectrum of thermally excited waves in systems with a heat flux, and on the new approach to the coupling between acoustic fields in separated bodies as well as a...

It is shown that the analysis of radiative heat transport across a nanoscale gap cannot ignore the correlation between radiations from the different sides of the gap. This correlation can be neglected in two cases: when the gap is considerably wider than the dominant wavelength of radiation and when the temperatures on different sides of the gap ar...

Over the past decades, there has been an increase in the demand for hard disk drives (HDDs) used in mobile computing devices. The work performance of a HDD mainly depends on its ability to withstand external disturbances in such applications. Studies of the HDD’s responses and failures during external shocks can be very beneficial for improving the...

We utilize thermal fly-height control (TFC) technology to perform in situ measurements of carbon overcoat wear at the angstrom level at the read–write area of magnetic recording heads. We also study the durability of the molecularly thin lubricated disk surface. Experimental findings reveal a linear relationship between the quantified carbon wear d...

The work performance of a hard disk drive (HDD) in mobile devices depends very much on its ability to withstand external disturbances. In this study, a detailed multibody structural model integrated with a complete air bearing model is developed to investigate the disk drive's response during external shocks. The head disk interface (HDI) failure m...

In this study we employ a numerical approach to explore the touchdown patterns of a thermal-flying-height-control (TFC) slider. Depending on the roughness of the head disk interface and thickness of the lubricant layer a TFC slider can experience different stages during touchdown. Three different touchdown patterns are shown. With a rougher interfa...

Test stand experiments were performed in which 44 μm stainless steel particles and 0.3 μm alumina particles were introduced at the head-disk interface (HDI) of hard disk drives (HDD), and their damage to the HDI was observed and evaluated. An Olympus HDI reliability tester was used to fly the sliders at different radii. Optical microscopy, atomic f...

Bit Patterned media (BPM) recording is one of the potential technologies to be used in future disk drives in order to increase the areal density to 5 Tbit/in2. But one of the main obstacles for BPM is to achieve dynamic stability of the air bearing slider at the head-disk interface (HDI). In this paper we first use a direct simulation method to che...

The areal data density of magnetic recording hard disk drives (HDDs) increases year by year, following a trend similar to Moore’s law. However, the increase is not unbounded and there are some physical limits. As the density increases, the size of each magnetic grain shrinks. Finally the magnetic grain will be no longer thermally stable due to what...

A new, local-adaptive, grid-generating algorithm is developed and integrated with the multigrid control volume method to simulate the steady flying state of the air bearing sliders in hard disk drives (HDDs) accurately and efficiently. Local finer meshes (mesh dimension decreases to half) are created on the nodes of the current finest grids that ha...

A new, local-adaptive, grid-generating algorithm is developed and integrated with the multigrid control volume method to simulate the steady flying state of the air bearing sliders in hard disk drives (HDDs) accurately and efficiently. Local finer meshes (mesh dimension decreases to half) are created on the nodes of the current finest grids that ha...

The paper discusses the common physical origin of heat conductance and heat radiation, proposes a simple model of micro and nanoscale heat transport caused by Casimir/van der Waals intermolecular forces, and addresses some difficulties arising in common applications of the conventional theory of heat radiation to micro and nano scale systems.

Accurate touchdown power detection is a prerequisite for read-write head-to-disk spacing calibration and control in current hard disk drives, which use the thermal fly-height control slider technology. The slider air bearing surface and head gimbal assembly design have a significant influence on the touchdown behavior, and this paper reports experi...

With the wide application of thermal flying-height control (TFC) technology in the hard disk drive industry, the head-disk clearance can be controlled to as low as ~1 nm. At this ultra-low clearance, the air bearing slider is subject to relatively large interfacial forces, and it experiences more complicated dynamics, compared with the flying case....

Future magnetic storage density targets (>4 Tb/in. 2) require subnanometer physical clearances that pose a tremendous challenge to the head disk interface (HDI) design. A detailed understanding of slider-lubricant interactions at small clearances and contact is important to not only address magnetic spacing calibration and long term HDI reliability...

For a heat assisted magnetic recording system to be successful, it must deliver heat to a small spot on a magnetic disk without being damaged by the applied power. This paper shows that such conditions may not be easily attained in systems that use laser energy and plasmonic near field transducers. It is also shown that the analysis and design of t...

This paper compares different mechanisms of heat transport across nano-scale gaps and discusses the role of electromagnetic phenomena in heat transport in general nano-scale layered structures. The results of the analysis suggest that heat transfer across sub-5 nm gaps like that appearing in prototypes of heat assisted magnetic recording (HAMR) sys...

We report experimental findings and simulation results that identify distinct dynamical phases during the light touchdown between the flying head and ultra-thin perfluoropolyether lubricant layer in resolution of Angstroms. Using an accurately controlled power supply with thermal fly-height control sliders, we observe that during light touchdown, t...

A novel method of carbon embedding ($\leq$1 nm) is used as a surface modification technique to produce overcoat free media surfaces. The filtered cathodic vacuum arc technique at ion energy of 90 eV is used to embed carbon in the top surface of a $\sim$25 nm iron/platinum (FePt) film. Transport of ions in matter (TRIM) simulations and X-ray photoel...

This paper describes equilibrium ensembles of thermally excited electromagnetic fields in layered media. The obtained results complement Planck's law of thermal radiation that determines the spectrum of the radiation but supplies little information about the ensemble of eigenfields (normal modes) excited in the medium. The developments regarding th...

Heat exchange between closely positioned bodies has become an important issue for many areas of modern technology including, but not limited to, integrated circuits, atomic force microscopy, and high-density magnetic recording, which deal with bodies separated by gaps as narrow as a few nanometers. It is now recognized that heat transport across a...

Optical imaging and photolithography promise broad applications in nano-electronics, metrologies, and single-molecule biology. Light diffraction however sets a fundamental limit on optical resolution, and it poses a critical challenge to the down-scaling of nano-scale manufacturing. Surface plasmons have been used to circumvent the diffraction limi...

Supplementary Online Material (SOM)

Planck's law of thermal radiation is limited to equilibrium systems that have a definite temperature and do not carry any heat flux. Here we extend it to steady-state systems with a constant heat flux. The obtained formulas explicitly describe the spectrum of thermal radiation in every direction and provide a sound basis for the self-consistent ana...

The transfer of perfluoropolyether (PFPE) lubricant from the disk surface to the slider as a function of head-disk clearance has been investigated experimentally. The effects of lubricant thickness, bonding ratio, molecular polarity, and main chain stiffness on the lubricant transfer rate and the critical clearance below which lubricant transfer ge...

Lubricant distribution and recovery for near contact and contact recording conditions are experimentally investigated using thermal fly-height control (TFC) sliders. Contact between the protruded center pad and the disk lubricant causes a thickness modulation (rippling) together with lubricant depletion that grows with contact duration. Slider dyna...

Heat exchange between closely positioned bodies has become an important issue for such areas of modern technology as integrated circuits, atomic force microscopy, and high-density magnetic recording, which deal with bodies separated by gaps as narrow as a few nanometers. This paper shows that if the gap's width is below a certain value, estimated a...

Bit patterned media (BPM) recording is one of the promising techniques for future disk drives in order to increase the areal density above 1Tbit/in2. However, the BPM can change the topography of the disk surface and thus have an effect on the flying characteristics of the air bearing sliders. So achieving a stable flying attitude at the hard disk...

This paper develops a novel approach to Kapitsa thermal resistance which extends Khalatnikov's acoustic mismatch theory by inclusion of a previously excluded broad class of acoustic waves that violate the Sommerfeld radiation condition, which is essential for the theory of sound but is not relevant for the analysis of heat transport. This extension...

Filling hard disk drives with air-helium gas mixtures instead of pure helium can balance performance improvement, such as reduced power cost, increased capacity and improved reliability, against manufacturing cost increase. A consistent approach is proposed here to investigate the flying performance of thermal flying height control sliders flying i...

Thermal flying-height control (TFC) is now a key technology used in hard-disk drives (HDD) as an effective way to push the magnetic spacing to sub-5nm. Precise control of the TFC sliders’ actuated flying-height (FH) is a major consideration in improving the read/write capability as well as reducing the reliability problem. In this paper, we investi...

The thermal flying height control (TFC), aka dynamic fly height (DFH), technique has been recently used in the head disk interface of hard disk drives to obtain a lower head-media spacing. The air bearing cooling effect, i.e., the heat conduction between the slider and the air film, has been incorporated in the numerical thermal–mechanical simulati...

This Letter generalizes the well-known acoustic mismatch theory of interface thermal resistance by inclusion into consideration a broad class of thermal vibrations that were excluded from that theory by the imposition in it of the Sommerfeld radiation condition, which is required for the theory of sound but is not relevant for the analysis of heat...

This paper generalizes the well-known acoustic mismatch theory of Kapitsa interface thermal resistance by taking into consideration a broad class of thermal vibrations that were excluded from that theory by the imposition of the Sommerfeld radiation condition, which is required for the theory of sound but is not relevant for the analysis of heat tr...

Thermal flying-height control (TFC) sliders have been recently used in commercial hard disk drives (HDDs) to increase the HDDs’ capacity. The design of this new class of sliders depends on the numerical prediction of their flying performance, which requires a model for heat flux on the surface of the slider facing the disk. The currently widely use...

Recent experiments report that the radiative heat conductance through a narrow vacuum gap between two flat surfaces increases as the inverse square of the width of the gap. Such a significant increase of thermal conductivity has attracted much interest because of numerous promising applications in nanoscale heat transfer and because of the lack of...

When the magnetic spacing in hard disk drives is reduced to sub-3nm, contact between the slider and disk becomes inevitable. Stability analysis is used in this study to investigate the head–disk interface (HDI) stability of thermal fly-height control (TFC) sliders in light contact with the disk lubricant or solid roughness. We implement an improved...

Thermal fly-height control sliders that are capable of subnanometer level actuation are used to investigate the vertical, down-track, and off-track slider dynamics in slider-disk lubricant contact. Slider-lubricant contact introduces significant excitation in all three directions, and the slider dynamics is dependent on the degree of lubricant-cont...

Optical lithography has been the key for continuous size reduction of semiconductor devices and circuits manufacturing. Although the industry is continually improving the resolution, optical lithography becomes more difficult and less cost effective in satisfying the ever increasing demands in nano-manufacturing. Besides manufacturing, the dramatic...

The requirement of higher storage density in hard disk drives is pushing the head-to-media spacing(HMS) to become ever smaller. Currently, thermal protrusion at the transducer that is realized by the heating element in dynamic fly-height(DFH) sliders can be used to control the HMS by applying controllable electrical power. Thus, just how low the sl...

This paper develops an analytically tractable acoustics model of thermal resistance of interfaces between dissimilar materials. It shows that a consistent development of the concept that heat in dielectrics is carried by lattice vibrations inevitably leads to the conclusion that heat-carrying acoustic waves must obey the introduced principle of hea...

Near or partial contact sliders are designed for the areal recording density of 1 Tbit/in.(2) or even higher in hard disk drives. The bouncing vibration of an air bearing-slider in near or partial contact with the disk is numerically analyzed using three different nonlinear slider dynamics models. In these three models, the air bearing with contact...

Lubricant distribution and recovery for near contact and contact recording conditions are experimentally investigated using Thermal Fly-height Control (TFC) sliders. Contact between the protruded center pad and the lubricant layer causes a thickness modulation together with lubricant depletion that grows with contact duration. In experiments using...

This letter employs established approaches to calculate the physical properties of the air-helium gas mixtures and investigates the thermal flying-height control slider’s flying performance in these environments. It is found that at a fixed heater power, the slider’s flying height first increases and then decreases with the fraction of helium in th...

As dynamic fly-height (DFH) sliders with active flying-height (FH) control using local thermal expansion caused by a heating element were introduced in hard disk drives recently, the minimum clearance between the head and disk has been reduced to sub-3-nm. To achieve a higher recording density, the clearance will have to become even smaller, which...

A six-degree-of-freedom slider dynamic simulator is developed to analyze the slider’s motion in the vertical, pitch, roll, yaw, length and width directions. The modified time-dependent Reynolds equation is used to model the air bearing and a new second order slip model is used for a bounded contact air bearing pressure. The simulator considers the...

The air-bearing shear force in the head–disk interface (HDI) of hard disk drives is a dominant factor determining the motion and instability of the lubricant layer, which plays an important role in drive reliability. In this communication, an analytical formula, which is applicable to the flow of an arbitrarily rarefied gas in the HDI and is more g...

The temperature inside modern hard disk drives (HDDs) can become as high as 100°C during operation. The effects of such high temperatures on the slider’s flying attitude and the shear forces on the slider and the disk are investigated in this paper. General formulae for the shear forces are derived, and the generalized Reynolds equation is modified...

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-h...

Prediction of the steady state flying height and attitude of air-bearing sliders in hard disk drives via simulations is the basis of their design process. Over the past few years air-bearing surfaces have become increasingly complex incorporating deep etches and steep wall profiles. In this paper we present a novel method of solving the inverse pro...

A reliable model of the heat transfer at the air bearing surface of a flying head slider is important for treating thermomechanical aspects of the molecular gas lubrication system in today’s hard disk drives. This article proposes a new model for heat transfer in the head disk interface, which considers both the heat conduction and viscous dissipat...

By using light to assist the recording process, hard disk drive capacity could potentially be increased by two orders of magnitude. The idea is to heat the magnetic medium locally, thus temporarily lowering its resistance to magnetic polarization.

In this paper, we derive analytical formulas for the force and torque on a spherical particle in a weak shear flow of a highly rarefied gas. The rotation axis of the particle is not restricted with regard to its direction. So this paper is an extension of our previous paper [N. Liu and D. Bogy, Phys. Fluids 20, 107102 (2008)] where the rotation axi...

Simulation of particle motion in the Head Disk Interface (HDI) aids in the understanding of the contamination process on a slider, which is critical for achieving higher areal data densities in hard disk drives. In this paper, the boundary effect—the presence of the slider and the disk—on particle motion in the HDI is investigated. A correction fac...

To enable the smaller slider-disk spacing that is required for the continual increase in data storage density, the interaction between the slider and the lubricant layer must be understood. In this paper, an interesting experimental phenomenon of sudden lubricant droplet transfer from the slider to the disk is reported and investigated. This phenom...

As the head-disk spacing is reduced in order to achieve higher areal density, dynamic stability of the slider is compromised by a variety of proximity interactions. One of the key factors is the disk topography, which provides dynamic excitation to the low-flying sliders and strongly influences the dynamics and stability of the slider. Several expe...

Slip-corrected Reynolds equations have not been widely used in the air bearing simulations for the head-disk interface in hard disk drives since Fukui and Kaneko [Trans ASME J Tribol 110:253–262, 1988] published a more accurate generalized lubrication equation (FK model) based on the linearized Boltzmann equation for molecular gas lubrication. Howe...

Thermal protrusion of the heating element built in the DFH slider can be used to control the head-to-media spacing (HMS) by applying controllable electrical power. It is very convenient to obtain ultra-low flying height (FH) and make slight contact with the disk using such a slider. In this study, we achieved 1 nm clearance flying over the disk usi...

Particle contamination on a slider in a hard disk drive (HDD) affects the HDD’s reliability. With the introduction of the thermal flying-height control (TFC) slider, the temperature in the head–disk interface (HDI) becomes non-uniform, which induces a temperature-gradient dependent force on particles moving in the HDI. The present article investiga...