The Physics of Organic Superconductors

The upper temperature for superconductivity in organic conductors has increased from 1 kelvin in 1980, when the phenomenon was discovered in the quasi-one-dimensional cation radical salt tetramethyltetraselenafulvalene phosphorus heptafluoride to 12 kelvin in a new series of organic salts that show nearly two-dimensional electronic properties. These superconductors are attracting interest because of the wide range of new phenomena that they exhibit, including the competition between various ground states, the influence of a magnetic field on a quasi-one-dimensional conductor, the quantization of the Hall effect in a three-dimensional material, the giant magnetoresistance effects related to the two-dimensional nature of the Fermi surface of some materials, and the coherent voltage oscillation of a spin-modulated ground state. Furthermore, there is reason to believe that organic conductors with high superconducting transition temperatures could be produced in the near future. The recent finding of superconductivity in "fullerene" doped with alkali metals supports this optimism.