Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Study: Quantum fluctuations are key in superconductors

Abstract:
First direct evidence of quantum critical point in iron-based 'pnictides'

Study: Quantum fluctuations are key in superconductors

Houston, TX | Posted on January 8th, 2010

New experiments on a recently discovered class of iron-based superconductors suggest that the ability of their electrons to conduct electricity without resistance is directly connected with the magnetic properties of those electrons.

Results of the experiments appear in the Jan. 8 issue of Physical Review Letters. The tests, which were carried out by a team of U.S. and Chinese physicists, shed light on the fundamental nature of high-temperature superconductivity, said Rice physicist Qimiao Si, a co-author on the study.

If better understood, high-temperature superconductors could be used to revolutionize electric generators, MRI scanners, high-speed trains and other devices.

In the study, scientists from Rice University, the University of Tennessee, Oak Ridge National Laboratory (ORNL), the National Institute of Standards and Technology (NIST), the Chinese Academy of Sciences' Institute of Physics and Renmin University in Beijing examined several iron-arsenide compounds. These are the "undoped" parents of the iron "pnictides" (pronounced: NICK-tides), a class of materials that were found to be high-temperature superconductors in 2008.

The experiments set out to test theoretical predictions that Si and collaborators published in the Proceedings of the National Academy of Sciences last March. They predicted that varying the size of some atoms in the parent compounds could allow physicists to tune the material's quantum fluctuations. These types of fluctuations can create tipping points called magnetic "quantum critical points," a state that exists when a material is at the cusp of transitioning from one quantum phase to another.

Using neutron-scattering facilities at NIST and ORNL, the team bombarded the materials with neutrons to decipher their structural and magnetic properties. The tests, which supported Si's theoretical predictions, determined that the strength of magnetic order in the materials was reduced when arsenic atoms were replaced with slightly smaller phosphorus atoms.

"We found the first direct evidence that a magnetic quantum critical point exists in these materials," Si said.

The results were made possible by the efforts of Nanlin Wang, a physicist from the Chinese Academy of Sciences' Institute of Physics, and his research group. They created a series of samples with varying amounts of phosphorous substituting for arsenic.

The discovery of high-temperature superconductivity in copper-oxide ceramics in 1986 led physicists to realize that quantum effects in electronic materials were far more complex than anticipated. One of these effects is quantum criticality. Criticality occurs near a tipping point that a material goes through when it changes phases. Many phase changes -- like ice melting into water -- occur because of thermal fluctuations. But quantum criticalities and quantum phase changes arise solely from quantum fluctuations.

"Our finding of a quantum critical point in iron pnictides opens the door for new avenues of research into this important class of materials," said University of Tennessee/ORNL physicist Pengcheng Dai, a neutron scattering specialist.

Si said, "The evidence from this study bolsters the hypothesis that high-temperature superconductivity in the iron pnictides originates from electronic magnetism. This should be contrasted to conventional low-temperature superconductivity, which is caused by ionic vibrations."

The Rice research was supported by the National Science Foundation and the Robert A. Welch Foundation.

####

About Rice University
Located in Houston, Rice University is consistently ranked one of America's best teaching and research universities. Known for its "unconventional wisdom," Rice is distinguished by its: size -- 3,102 undergraduates and 2,237 graduate students; selectivity -- 12 applicants for each place in the freshman class; resources -- an undergraduate student-to-faculty ratio of 5-to-1; sixth largest endowment per student among American private research universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work.

For more information, please click here

Contacts:
Jade Boyd
713-348-6778

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Nanometrics to Participate in the 9th Annual CEO Investor Summit 2017: Accredited investor and publishing research analyst event held concurrently with SEMICON West and Intersolar 2017 in San Francisco June 27th, 2017

NMRC, University of Nottingham chooses the Quorum Q150 coater for its reliable and reproducible film thickness when coating samples with iridium June 27th, 2017

Picosunís ALD solutions enable novel high-speed memories June 27th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Atomic imperfections move quantum communication network closer to reality June 25th, 2017

Research accelerates quest for quicker, longer-lasting electronics: UC Riverside-led research makes topological insulators magnetic well above room temperatures June 25th, 2017

U.S. Air Force Research Lab Taps IBM to Build Brain-Inspired AI Supercomputing System: Equal to 64 million neurons, new neurosynaptic supercomputing system will power complex AI tasks at unprecedented speed and energy efficiency June 23rd, 2017

Rice U. chemists create 3-D printed graphene foam June 22nd, 2017

Possible Futures

Physicists make quantum leap in understanding life's nanoscale machinery June 27th, 2017

Atomic imperfections move quantum communication network closer to reality June 25th, 2017

Research accelerates quest for quicker, longer-lasting electronics: UC Riverside-led research makes topological insulators magnetic well above room temperatures June 25th, 2017

U.S. Air Force Research Lab Taps IBM to Build Brain-Inspired AI Supercomputing System: Equal to 64 million neurons, new neurosynaptic supercomputing system will power complex AI tasks at unprecedented speed and energy efficiency June 23rd, 2017

Academic/Education

Oxford Instruments congratulates Lancaster University for inaugurating the IsoLab, built for studying quantum systems June 20th, 2017

The 2017 Winners for Generation Nano June 8th, 2017

MIT Energy Initiative awards 10 seed fund grants for early-stage energy research May 4th, 2017

Bar-Ilan University to set up quantum research center May 1st, 2017

Announcements

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Nanometrics to Participate in the 9th Annual CEO Investor Summit 2017: Accredited investor and publishing research analyst event held concurrently with SEMICON West and Intersolar 2017 in San Francisco June 27th, 2017

NMRC, University of Nottingham chooses the Quorum Q150 coater for its reliable and reproducible film thickness when coating samples with iridium June 27th, 2017

Picosunís ALD solutions enable novel high-speed memories June 27th, 2017

Tools

Nanometrics to Participate in the 9th Annual CEO Investor Summit 2017: Accredited investor and publishing research analyst event held concurrently with SEMICON West and Intersolar 2017 in San Francisco June 27th, 2017

NMRC, University of Nottingham chooses the Quorum Q150 coater for its reliable and reproducible film thickness when coating samples with iridium June 27th, 2017

New TriboLab CMP Provides Cost-Effective Characterization of Chemical Mechanical Wafer Polishing Processes: Bruker Updates Industry-Standard CP-4 Platform for Most Flexible and Reliable Testing June 27th, 2017

Researchers developed nanoparticle based contrast agent for dual modal imaging of cancer June 21st, 2017

Alliances/Trade associations/Partnerships/Distributorships

U.S. Air Force Research Lab Taps IBM to Build Brain-Inspired AI Supercomputing System: Equal to 64 million neurons, new neurosynaptic supercomputing system will power complex AI tasks at unprecedented speed and energy efficiency June 23rd, 2017

Cambridge Nanotherm partners with Inabata for global sales and distribution June 20th, 2017

Thought Leaders and Experts Join National Graphene Association Advisory Board June 16th, 2017

Microsoft, Purdue collaborate to advance quantum computing May 30th, 2017

Quantum nanoscience

Physicists make quantum leap in understanding life's nanoscale machinery June 27th, 2017

Atomic imperfections move quantum communication network closer to reality June 25th, 2017

Oxford Instruments congratulates Lancaster University for inaugurating the IsoLab, built for studying quantum systems June 20th, 2017

In atomic propellers, quantum phenomena can mimic everyday physics June 1st, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project