Energy News  
Theories Of High-Temperature Superconductivity Violate Pauli Principle

File image of high-temperature super conducting lattice.
by Staff Writers
Champaign IL (SPX) Mar 28, 2005
Scientists seeking to explain high-temperature superconductivity have been violating the Pauli exclusion principle, a team of researchers from the University of Illinois at Urbana-Champaign and Rutgers University report. Any theory that does not embrace the Pauli principle has a lot of explaining to do, they say.

The basic organizing precept behind the periodic table is the Pauli principle, which says that electrons with the same spin cannot occupy the same energy state.

The Pauli principle leads to the shell structure of atoms, and is inviolate for electronic systems. Many researchers, however, have been breaking this important rule when proposing theories to explain the mechanism behind high-temperature superconductivity.

"Within a class of materials known as doped Mott insulators, such as the high-temperature copper-oxide superconductors, the Pauli principle emerges as a sum-rule connecting high- and low-energy scales," said Philip Phillips, a professor of physics at the University of Illinois at Urbana-Champaign, who will present the team's findings at the spring meeting of the American Physical Society, to be held in Los Angeles, March 21-25.

"It is standard practice in physics to separate high- and low-energy scales through a procedure known as renormalization," Phillips said.

"We have shown that this procedure changes the statics of the excitations within doped Mott insulators, resulting in a violation of the Pauli principle. Since such a violation is not possible, we conclude that high- and low-energy scales are inextricably linked in doped Mott insulators."

Unlike low-temperature superconductors, which are metals, high-temperature superconductors are insulators in their normal state. Even more puzzling, half of the electron states are empty.

"Since there are plenty of available positions for electrons, you would think these materials should be metallic," Phillips said. "Even though there are many unoccupied states, strong electron interactions cause them to be insulators."

Strong electron interaction is the key to understanding Mott insulators, Phillips said.

"The interactions cause a mixing of the high- and low-energy scales. Because the electrons at all energy levels are interconnected, performing renormalization will be done at a price -- in this case at the expense of the Pauli exclusion principle."

Phillips and his colleagues -- Illinois graduate student Dimitrios Galanakis and former graduate student Tudor D. Stanescu (now a postdoctoral research associate at Rutgers University) -- also suggest that the mixing of high- and low-energy scales might explain the absence of well-resolved electron-like features in the normal state of the copper-oxide superconductors.

Experiments have demonstrated that removing an electron from a metal results in a very narrow peak in the photoemission spectrum. Removing an electron from the normal state of a high-temperature superconductor results in a very broad feature.

"If you remove the high-energy scale through the process of renormalization, the spectral features are very sharp," Phillips said. "But if you retain it, the features are very broad. If the physics changes when you remove the high-energy scale, then renormalization is out the window. The Pauli principle can not be violated."

This work also appeared in the Dec. 31, 2004, issue of the journal Physical Review Letters.

Community
Email This Article
Comment On This Article

Related Links
University of Illinois at Urbana-Champaign
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express
Powering The World in the 21st Century at Energy-Daily.com



Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


Europe Debates Nuclear Energy
Washington (UPI) Jan 11, 2006
European Union countries are starting to rethink their opposition to nuclear energy amid a dispute between Russia and Ukraine over natural gas supplies, but energy analysts say a switch still lacks a green light.







  • Theories Of High-Temperature Superconductivity Violate Pauli Principle
  • Membraneless Fuel Cell Is Tiny, Versatile
  • Big Hopes For Tiny, New Hydrogen Storage Material
  • Canada's Wind Power Capacity Jumps Almost 25 Percent

  • Taiwan Defies Safety Warnings And Installs Reactor At Nuclear Power Plant
  • New Nuclear Friction In West
  • Iran Says Ready To Sign Key Deal With Russian On Nuclear Plant
  • Tsunami Makes India's Nuke Workers Jittery





  • NASA Uses Remotely Piloted Airplane To Monitor Grapes



  • Who Will Win: Boeing Or Airbus?
  • Airbus, Space Activities Lift EADS 2004 Profit By 60 Percent
  • Fossett Commits To Final Dash To Kansas
  • GlobalFlyer Approaches Pakistan In Round-The-World Flight

  • NASA plans to send new robot to Jupiter
  • Los Alamos Hopes To Lead New Era Of Nuclear Space Tranportion With Jovian Mission
  • Boeing Selects Leader for Nuclear Space Systems Program
  • Boeing-Led Team to Study Nuclear-Powered Space Systems

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement