Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ultra-high-density data storage may become practical with breakthrough in nanoscale magnetic sensors

03.02.2003


A simpler and more reliable manufacturing method has allowed two materials researchers to produce nanoscale magnetic sensors that could increase the storage capacity of hard disk drives by a factor of a thousand. Building on results reported last summer, the new sensors are up to 100 times more sensitive than any current alternative technology.

Susan Hua and Harsh Deep Chopra, both professors at the State University of New York at Buffalo, report in the February issue of Physical Review B on their latest experiments with nanoscale sensors that produce, at room temperature, unusually large electrical resistance changes in the presence of small magnetic fields. The work is supported by the National Science Foundation (NSF), an independent federal agency that supports fundamental research and education across all fields of science and engineering.

"We first saw a large effect of over 3,000 percent resistance change in small magnetic fields last July," Chopra said. "That was just the tip of the iceberg. These results point to the beautiful science that remains to be discovered." The largest signal they have seen is 33 times larger than the effect they reported last summer, which corresponds to a 100,000 percent change in resistance.



As stored "bits" of data get smaller, their magnetic fields get weaker, which makes individual bits harder to detect and "read." Packing more bits onto the surface of a computer disk, therefore, requires reliable sensors that are smaller, yet more sensitive to the bit’s magnetic field. Hua and Chopra’s nanoscale sensor seems to be ideally suited to the task.

For comparison, the technology in today’s hard disk drives relies on signals as weak as a 20 percent change in resistance. In other words, if sensor has a baseline signal of 1, an "off" bit causes Chopra and Hua’s sensors to spike at signal strength of -1,000, and an "on" bit registers +1,000. Current sensors, which only work on much larger bit sizes, would swing between an "off" signal of 0.8 and "on" of 1.2. The larger changes mean that the new sensors produce much more distinct and reliable signals than current technologies do, which would enable the bit size to be shrunk dramatically.

Chopra and Hua’s sensors have another advantage over other experimental techniques that are currently being studied: Because of the sensors’ high sensitivity at room temperature, they would be straightforward to adapt to work with existing technologies used by the $25 billion hard disk drive industry. Chopra predicts that their sensors would permit disk capacities on the order of terabits (trillions of bits) per square inch.

Their success builds on an effect called "ballistic magnetoresistance" (BMR). "Magnetoresistance" measures the change in electrical resistance when a device is placed in a magnetic field. Many types of magnetoresistance are being explored for sensors that might find use in hard disk drives. The magnetoresistance effect goes "ballistic" when an electron must cross a channel so narrow that the electron shoots straight through without scattering. In a normal wire, an electron zigzags its way through the material in a process called "diffusive" transport.

Chopra and Hua created their ballistic-effect sensors by forming nanoscale nickel "whiskers" between two larger nickel electrodes. Their current experiments include confirmation of the structure and composition of the whiskers with scanning electron microscopy.

The researchers suspect that the ballistic effect stems from pinch points, or constrictions, in the whiskers produced during manufacturing. The new manufacturing method, which also allowed them to reliably produce nanosensors with the desired effect, is therefore a key to Chopra and Hua’s latest success.

Chopra and Hua modified and adapted a method of producing controlled nanoscale wires originally developed b y Arizona State University’s Nongjian Tao, whose work is also supported by NSF. Tao’s electrodeposition method allowed Chopra and Hua to specify in advance the resistance they wanted from their nanoscale whiskers. They can now reproduce their contacts reliably and simply, as opposed to the hit-or-miss method they had used previously. "We have been consistently able to produce contacts with BMR effects of several thousand percent," Chopra said.

Besides disk drives, these types of sensors may also have biomedical applications. For example, the sensor’s electrical properties might be used to detect biomolecules in solution, even in low concentrations, according to Chopra. By attaching itself to the sensor, each type of biomolecule would impart its own "fingerprint" by changing the electrical signal of the nanocontact.

NSF Science Experts:
K.L. Murty
Tel.: 001-703-292-4935
E-mail: kmurty@nsf.gov
Shih Chi Liu
Tel.: 001-703-292-8360
E-mail: sliu@nsf.gov

David Hart | National Science Foundation
Further information:
http://www.nsf.gov/od/lpa/news/02/pr0255.htm
http://www.nsf.gov
http://www.fastlane.nsf.gov/a6/A6Start.htm

More articles from Information Technology:

nachricht Smart Computers
21.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht AI implications: Engineer's model lays groundwork for machine-learning device
18.08.2017 | Washington University in St. Louis

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

What the world's tiniest 'monster truck' reveals

23.08.2017 | Life Sciences

Treating arthritis with algae

23.08.2017 | Life Sciences

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>