Forum for Science, Industry and Business
Sponsored by:     Siemens  n-tv 
Search our Site:

Topic (optional):

 

Home Reports Physics and Astronomy Content

Physicists Harness Disorder in Magnetic Sensors

next article
10.09.2008

University of Chicago scientists have discovered how to make magnetic sensors capable of operating at the high temperatures that ceramic engines in cars and aircraft of the future will require for higher operating efficiency than today's internal combustion technology.

 

The key to fabricating the sensors involves slightly diluting samples of a well-known semiconductor material, called indium antimonide, which is valued for its purity. Chicago’s Thomas Rosenbaum and associate Jingshi Hu, now of the Massachusetts Institute of Technology, have published their formula in the September issue of the journal Nature Materials.


Most magnetic sensors operate by detecting how a magnetic field alters the path of an electron. Conventional sensors lose this capability when subjected to temperatures reaching hundreds of degrees. Not so in the indium antimonide magnetosensors that Rosenbaum and Hu developed with support from the U.S. Department of Energy.

“This sensor would be able to function in those sorts of temperatures without any degradation,” said Rosenbaum, the John T. Wilson Distinguished Service Professor in Physics.

Rosenbaum’s research typically focuses on the properties of materials observed at the atomic level when subjected to temperatures near absolute zero (minus-460 degrees Fahrenheit). More than a decade ago, he led a team of scientists in experiments involving silver selenide and silver telluride, two materials that exhibited no magnetic response at low temperatures. But when the team introduced a tiny amount of silver (one part in 10,000) to the materials, their magnetic response skyrocketed.

In silver selenide and silver telluride, the magnetic response disappears at room temperature, which limits their technological applications. But Rosenbaum and Hu now have used two methods to recreate the effect at much higher temperatures in indium antimonide. Disordering the material—simply grinding it up and fusing it with heat—produces the effect. So does introducing impurities of just a few parts per million.

“What’s nice about it is that, first, it’s an unexpected phenomenon; and second, it’s a very useful one,” said University of Cambridge physicist Peter Littlewood. “Normally, in order to make large effects, you have to have pure samples.”

Before Rosenbaum and Hu’s latest experiments, two theories dueled to explain the effect. In 2003, Littlewood and Meera Parish, now a postdoctoral fellow at the Princeton Center for Theoretical Physics, explained the effect using classical physics, the laws of nature that govern physics above the atomic scale. Nobel laureate Alexei Abrikosov of Argonne National Laboratory devised an explanation based on quantum physics, the dominant physics at ultrasmall scales.

“We’ve shown that both theories work, just in different regimes,” Rosenbaum said.

Littlewood lauded the sequence of events as an example of how science ought to work. “There’s a discovery of a result. There’s a theory about it. Further experiments are done to test the theory. They work and that provokes another idea, and you bounce to and fro,” Littlewood said. “That’s how we like to describe science progressing. One is rarely lucky enough to do that over a long period.”

Steve Koppes | Source: Newswise Science News
Further information: www.uchicago.edu

next article

More articles from Physics and Astronomy:

nachricht Quantum gas microscope offers glimpse of quirky ultracold atoms
06.11.2009 | Harvard University

nachricht Carbon Atmosphere Discovered on Neutron Star
06.11.2009 | Chandra X-ray Observatory

All articles from Physics and Astronomy >>>

B2B Search

Product / Service
Company / Organisation

Latest News

Airborne nitrogen shifts aquatic nutrient limitation in pristine lakes

06.11.2009 | Studies and Analyses

Genome sequence for the domestic horse to be unveiled

06.11.2009 | Life Sciences

New Study in Geology Uses Satellite Imagery to Identify Active Magma Systems in East Africa’s Rift Valley

06.11.2009 | Earth Sciences

VideoLinks

Event News

Texas Tech University Hosts Major Textile Conference in India

06.11.2009 | Event News

Brief Highlights of the Fluid Dynamics Conference, Minneapolis

30.10.2009 | Event News

EUROSAFE Forum 2009 Brussels: "Safety Implications of an Increased Demand for Nuclear Energy"

29.10.2009 | Event News