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 The TU Ilmenau develops tomorrow’s chip technology today
27.04.2017 | Technische Universität Ilmenau

nachricht Five developments for improved data exploitation
19.04.2017 | Deutsches Forschungszentrum für Künstliche Intelligenz GmbH, DFKI

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>