Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Electrons are not enough: Cuprate superconductors defy convention

Graph showing the breakdown of Luttinger's theorem in the normal state of cuprate superconductors.  The horizontal axis is the expected number of mobile electrons while is the vertical axis is the measured number.  The two should be equal if the theorem were true.Graphic by Philip Phillips
Graph showing the breakdown of Luttinger's theorem in the normal state of cuprate superconductors. The horizontal axis is the expected number of mobile electrons while is the vertical axis is the measured number. The two should be equal if the theorem were true.

Graphic by Philip Phillips

Abstract:
To engineers, it's a tale as old as time: Electrical current is carried through materials by flowing electrons. But physicists at the University of Illinois and the University of Pennsylvania found that for copper-containing superconductors, known as cuprates, electrons are not enough to carry the current.

Electrons are not enough: Cuprate superconductors defy convention

Champaign, IL | Posted on March 18th, 2013

"The story of electrical conduction in metals is told entirely in terms of electrons. The cuprates show that there is something completely new to be understood beyond what electrons are doing," said Philip Phillips, a professor of physics and of chemistry at the U. of I.

In physics, Luttinger's theorem states that the number of electrons in a material is the same as the number of electrons in all of its atoms added together. Electrons are the sub-atomic particles that carry the current in a conductive material. Much-studied conducting materials, such as metals and semiconductors, hold true to the theorem.

Phillips' group works on the theory behind high-temperature superconductors. In superconductors, current flows freely without resistance. Cuprate superconductors have puzzled physicists with their superconducting ability since their discovery in 1987.

The researchers developed a model outlining the breakdown of Luttinger's theorem that is applicable to cuprate superconductors, since the hypotheses that the theorem is built on are violated at certain energies in these materials. The group tested it and indeed found discrepancies between the measured charge and the number of mobile electrons in cuprate superconductors, defying Luttinger.

"This result is telling us that the physics cannot be described by electrons alone," Phillips said. "This means that the cuprates are even weirder than previously thought: Something other than electrons carries the current."

"Theorists have suspected that something like this was true but no one has been able to prove it," Phillips said. "Electrons are charged. Therefore, if an electron does not contribute to the charge count, then there is a lot of explaining to do."

Now the researchers are exploring possible candidates for current-carriers, particularly a novel kind of excitation called unparticles.

Phillips, U. of I. undergraduate student Kiaran Dave (now a graduate student at MIT) and University of Pennsylvania professor Charles Kane published their findings in the journal Physical Review Letters. The National Science Foundation and the Center for Emergent Superconductivity (through a DOE Energy Frontiers Research Center) supported this work.

####

For more information, please click here

Contacts:
Liz Ahlberg
Physical Sciences Editor
217-244-1073


Philip Phillips
217-244-6703

Copyright © University of Illinois at Urbana-Champaign

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 Links

The paper, “Absence of Luttinger’s Theorem due to Zeros in the Single-Particle Green Function,” is available online:

Related News Press

News and information

Light pulses control graphene's electrical behavior: Finding could allow ultrafast switching of conduction, and possibly lead to new broadband light sensors August 1st, 2014

President Obama Meets U.S. Laureates of 2014 Kavli Prizes August 1st, 2014

Stanford researchers seek 'Holy Grail' in battery design: Pure lithium anode closer to reality with development of protective layer of interconnected carbon domes August 1st, 2014

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

Superconductivity

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

UCF Nanotech Spinout Developing Revolutionary Battery Technology: Power the Next Generation of Electronics with Carbon July 23rd, 2014

Physics

Watching Schrödinger's cat die (or come to life): Steering quantum evolution & using probes to conduct continuous error correction in quantum computers July 30th, 2014

Flexible Metamaterial Absorbers July 29th, 2014

Measuring the Smallest Magnets July 28th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Light pulses control graphene's electrical behavior: Finding could allow ultrafast switching of conduction, and possibly lead to new broadband light sensors August 1st, 2014

President Obama Meets U.S. Laureates of 2014 Kavli Prizes August 1st, 2014

Stanford researchers seek 'Holy Grail' in battery design: Pure lithium anode closer to reality with development of protective layer of interconnected carbon domes August 1st, 2014

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

Discoveries

Iranian Scientists Produce Cobalt–Alumina Ceramic Nano Inks August 1st, 2014

Light pulses control graphene's electrical behavior: Finding could allow ultrafast switching of conduction, and possibly lead to new broadband light sensors August 1st, 2014

Taking the guesswork out of cancer therapy: New molecular test kit predicts patient’s survival and drug response August 1st, 2014

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

Announcements

Light pulses control graphene's electrical behavior: Finding could allow ultrafast switching of conduction, and possibly lead to new broadband light sensors August 1st, 2014

President Obama Meets U.S. Laureates of 2014 Kavli Prizes August 1st, 2014

Stanford researchers seek 'Holy Grail' in battery design: Pure lithium anode closer to reality with development of protective layer of interconnected carbon domes August 1st, 2014

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 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