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 Gecko adhesion technology moves closer to industrial uses
13.12.2017 | Georgia Institute of Technology

nachricht New silicon structure opens the gate to quantum computers
12.12.2017 | Princeton University

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Gecko adhesion technology moves closer to industrial uses

13.12.2017 | Information Technology

Columbia engineers create artificial graphene in a nanofabricated semiconductor structure

13.12.2017 | Physics and Astronomy

Research reveals how diabetes in pregnancy affects baby's heart

13.12.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>