Data storage: Measuring the downside of downsizing

Jul 31, 2013
Data storage: Measuring the downside of downsizing
Understanding how much lubricant is transferred from the rotating disk to the slider is crucial for designing better hard disk drives. Credit: iStockphoto/Thinkstock

To keep pace with the rapidly growing consumer demand for data storage, hardware engineers are striving to cram as much electronic information into as small a space as possible. Jinmin Zhao, Mingsheng Zhang and co‐workers at the A*STAR Data Storage Institute, Singapore, have now devised a technique to assess the impact of making these devices more compact. Insights resulting from this work will guide the future design of stable disk drives.

The primary components of a hard disk drive are a rotating disk coated with a thin film of and a magnetic head on a moving arm, also called a slider (see image). The slider includes magnetic write/read elements that can encode a single bit of binary information by altering the properties of the thin film at a small spot on the surface. A smaller spot enables a higher density of data storage.

Current technology is rapidly approaching one trillion bits per square inch, but this requires the separation between the head and disk to be less than 2 nanometers. This narrow requirement, however, creates its own problems. Lubricant used on the surface of the disk to protect it from corrosion can attach to the slider, which adversely affects the reliability of the . "We have carried out a systematic and quantitative study on how the variation of slider affects the accuracy of the measured thickness on the slider surface," says Zhang.

Zhao, Zhang and their co-workers analyzed a lubricant-coated slider using a technique known as spectroscopic ellipsometry. Measuring the reflected from a sample slider provided a highly accurate estimate of the thickness of the lubricant film. Ellipsometry is a fast and non-destructive technique that, unlike some of the alternative approaches, does not require ultra-high . This technique, however, does require accurate knowledge of the optical properties of the slider. A typical slider is made of and grains of titanium carbide of many different shapes and sizes; thus, its optical properties vary from position to position.

Zhao and the team's study demonstrated that the uncertainty in lubricant thickness is approximately proportional to the uncertainty in the slider's optical constants, and it becomes particularly pronounced for thicknesses below 2 nanometers.

"This lubricant transfer will be more serious in future heat-assisted magnetic recording," explains Zhang. "The next step in this research will focus on how to reduce the lubricant transfer, especially in this type of device."

Explore further: Engineers develop new methods to speed up simulations in computational grand challenge

More information: Zhao, J. M., Zhang, M. S., Yang, M. C. & Ji, R. Ellipsometric measurement accuracy of ultrathin lubricant thickness on magnetic head slider. Microsystem Technologies 18, 1283–1288 (2012). dx.doi.org/10.1007/s00542-012-1519-8

add to favorites email to friend print save as pdf

Related Stories

TDK sees hard drive breakthrough in areal density

Oct 03, 2012

(Phys.org)—TDK has realized increased areal density of its hard disk drives. TDK has set a new record, compared to previous areal density at 1Tbit/inch2, with the new stat of increased density to 1.5Tbit ...

Recommended for you

New insights found in black hole collisions

6 hours ago

New research provides revelations about the most energetic event in the universe—the merging of two spinning, orbiting black holes into a much larger black hole.

X-rays probe LHC for cause of short circuit

6 hours ago

The LHC has now transitioned from powering tests to the machine checkout phase. This phase involves the full-scale tests of all systems in preparation for beam. Early last Saturday morning, during the ramp-down, ...

Swimming algae offer insights into living fluid dynamics

9 hours ago

None of us would be alive if sperm cells didn't know how to swim, or if the cilia in our lungs couldn't prevent fluid buildup. But we know very little about the dynamics of so-called "living fluids," those ...

Fluctuation X-ray scattering

Mar 26, 2015

In biology, materials science and the energy sciences, structural information provides important insights into the understanding of matter. The link between a structure and its properties can suggest new ...

Hydrodynamics approaches to granular matter

Mar 26, 2015

Sand, rocks, grains, salt or sugar are what physicists call granular media. A better understanding of granular media is important - particularly when mixed with water and air, as it forms the foundations of houses and off-shore ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.