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Research reveals new aspects of superconductivity and correlated phenomena

Publicado em 14 abril 2018

Discovered accidentally over a century ago, the phenomenon of superconductivity inspired a technological revolution. In 1911, while studying the behavior of solid mercury supercooled to 4 K (-269 °C), Dutch physicist Heike Kamerlingh Onnes (1853-1926) observed for the first time that certain materials conduct electricity without resistance or losses at temperatures in the vicinity of absolute zero.

Interest revived in the 1980s when superconductivity was experimentally observed at much higher temperatures in the range of 90 K (-183 °C). This record was later surpassed, and scientists now seek superconductivity at room temperature.

Information - Background - Study - Solid - State This information provides the background for a study recently conducted by the Solid State Physics Group at São Paulo State University (UNESP) in Rio Claro, Brazil. The principal investigator was Valdeci Pereira Mariano de Souza. In addition to other researchers affiliated with UNESP, the team included scientists from Paris South University (Orsay) in France.

In Rio Claro, the research team used equipment purchased with support from the São Paulo Research Foundation - FAPESP to obtain the results, which provided the basis for an article published in Physical Review B.

Materials - Phase - Proximity - Mott - Insulating "In several materials, the superconductive phase is manifested in the proximity of what's known as the Mott insulating phase. The Mott metal-insulator transition is a sudden change in electrical conductivity that occurs at a given temperature when the Coulomb repulsion between electrons becomes comparable to the free-electron kinetic energy," said Mariano.

"When the Coulomb repulsion becomes relevant, the electrons that were itinerant become localized, and this minimizes the system's total energy. This electron localization is the Mott insulating phase. In some cases, an even more exotic process unfolds. Because of the interactions between electrons occupying neighboring sites in the network, the electrons rearrange themselves in the network in a non-homogeneous manner, and a so-called 'charge ordering phase' occurs. Our study addressed this kind of...

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