Maximizing Superconducting Critical Temperature

Researchers describe a new state of matter that could lead to high temperature superconductors.

AsianScientist (May 4, 2015) – An international research team, led by Professor Kosmas Prassides of Tohoku University, has investigated the electronic properties of the family of unconventional superconductors based on fullerenes which have the highest known superconducting critical temperature (Tc) among molecular superconductors.

In results published in the journal Science Advances, the team was able to demonstrate the guiding influence of the molecular electronic structure in controlling superconductivity and achieving the maximum Tc, opening the way to new routes in the search of new molecular superconductors with enhanced properties.

Currently, conventional metals are used for electricity transmission, but energy is lost as heat because of electrical resistance. In contrast, superconductors have no electrical resistance and can carry electricity without losing energy.

Unfortunately, existing superconducting materials only operate at low temperatures, sparking the search for new materials which can work at room temperature or higher. Most superconductors have simple structures built from atoms. But recently, superconductors made from molecules arranged in regular solid structures have been found.

The research team has addressed for the first time the relationship between the parent insulator, the normal metallic state above Tc and the superconducting pairing mechanism in a new family of chemically-pressurized fullerene materials. This is a key question in understanding all unconventional superconductors including the high-Tc cuprates, the iron pnictides and the heavy fermion systems.

Their work unveiled a new state of matter—the Jahn-Teller metal—and showed that when the balance between molecular and extended lattice characteristics of the electrons at the Fermi level is optimized, the highest achievable temperature for the onset of superconductivity is attained.

As synthetic chemistry allows the creation of new molecular electronic structures distinct from those in the atoms and ions that dominate most known superconductors, there is now strong motivation to search for new molecular superconducting materials.

The article can be found at: Zadik et al. (2015) Optimized Unconventional Superconductivity In A Molecular Jahn-Teller Metal.


Source: Tohoku University.
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