![]() ![]() Removing an electron from the normal state of a high-temperature superconductor results in a very broad feature. 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.Įxperiments have demonstrated that removing an electron from a metal results in a very narrow peak in the photoemission spectrum. Phillips and his colleagues - Illinois graduate student Dimitrios Galanakis and former graduate student Tudor D. 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." ![]() "The interactions cause a mixing of the high- and low-energy scales. Strong electron interaction is the key to understanding Mott insulators, Phillips said. "Even though there are many unoccupied states, strong electron interactions cause them to be insulators." "Since there are plenty of available positions for electrons, you would think these materials should be metallic," Phillips said. Even more puzzling, half of the electron states are empty. Unlike low-temperature superconductors, which are metals, high-temperature superconductors are insulators in their normal state. Since such a violation is not possible, we conclude that high- and low-energy scales are inextricably linked in doped Mott insulators." "We have shown that this procedure changes the statics of the excitations within doped Mott insulators, resulting in a violation of the Pauli principle. "It is standard practice in physics to separate high- and low-energy scales through a procedure known as renormalization," Phillips said. 31, 2004, issue of the journal Physical Review Letters. "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. Many researchers, however, have been breaking this important rule when proposing theories to explain the mechanism behind high-temperature superconductivity. The Pauli principle leads to the shell structure of atoms, and is inviolate for electronic systems. 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. Any theory that does not embrace the Pauli principle has a lot of explaining to do, they say. 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. ![]()
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