Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

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

Industrial Nanotech, Inc. to Publish PCAOB Audited Financials July 31st, 2014

Nanostructured metal-oxide catalyst efficiently converts CO2 to methanol: Highly reactive sites at interface of 2 nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products July 31st, 2014

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

Pressure probing potential photoelectronic manufacturing compound July 31st, 2014

Govt.-Legislation/Regulation/Funding/Policy

Study finds physical link to strange electronic behavior: Neutron measurements offer new clues about iron-based superconductor July 31st, 2014

Nanostructured metal-oxide catalyst efficiently converts CO2 to methanol: Highly reactive sites at interface of 2 nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products July 31st, 2014

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

Pressure probing potential photoelectronic manufacturing compound July 31st, 2014

Possible Futures

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Virus structure inspires novel understanding of onion-like carbon nanoparticles April 10th, 2014

Local girl does good March 22nd, 2014

Surface Characteristics Influence Cellular Growth on Semiconductor Material March 12th, 2014

Academic/Education

University of Manchester selects Anasys AFM-IR for coatings and corrosion research July 30th, 2014

Haydale Announces Collaboration Agreement with Swansea University’s Welsh Centre for Printing and Coatings (WCPC) July 12th, 2014

STFC takes delivery of the 100th Hitachi Tabletop SEM in the UK July 3rd, 2014

Innovation Management and the Emergence of the Nanobiotechnology Industry July 1st, 2014

Announcements

Industrial Nanotech, Inc. to Publish PCAOB Audited Financials July 31st, 2014

Nanostructured metal-oxide catalyst efficiently converts CO2 to methanol: Highly reactive sites at interface of 2 nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products July 31st, 2014

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

Pressure probing potential photoelectronic manufacturing compound July 31st, 2014

Tools

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

New imaging agent provides better picture of the gut July 30th, 2014

Nanometrics Reports Second Quarter 2014 Financial Results July 30th, 2014

New Objective Focusing Nanopositioner from nPoint July 30th, 2014

Alliances/Partnerships/Distributorships

Nature inspires a greener way to make colorful plastics July 30th, 2014

SouthWest NanoTechnologies Names NanoSperse as A SWeNT Certified Compounder July 29th, 2014

ACS Biomaterials Science & Engineering™: Brand-new journal names editor July 29th, 2014

A*STAR and industry form S$200M semiconductor R&D July 25th, 2014

Quantum nanoscience

Measuring the Smallest Magnets July 28th, 2014

Physicists Use Computer Models to Reveal Quantum Effects in Biological Oxygen Transport: The team solved a long-standing question by explaining why oxygen – and not deadly carbon monoxide – preferably binds to the proteins that transport it around the body. July 17th, 2014

Bending the rules: A UCSB postdoctoral scholar in physics discovers a counterintuitive phenomenon: the coexistence of superconductivity with dissipation June 29th, 2014

Singapore Researchers Use FEI Titan S/TEM to Link Plasmonics with Molecular Electronics: As described in the March 28 issue of Science, researchers discover quantum plasmonic tunneling – a phenomenon that may eventually lead to new, ultra-fast electrical circuits June 24th, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE