Abstract:
Superconductivity is a remarkable state of matter which does not have a clear explanation for the unconventional superconductors. This review focuses on organic superconductors, their properties, and proposed mechanism including the key ingredients for unconventional superconductivity. Most of the organic superconductors show a 2:1 stoichiometry; hence the carrier density of 0.5 is highlighted within this family. A New insulating state of Paired Electron Crystal (PEC), a mediator of the adjacent insulating state and the superconducting state, is introduced by the Hubbard model calculation for the strongly correlated electron-lattice systems. Also pointed out the coulomb enhanced pair-pair correlation compared to non-interacting limit is a signature for the superconducting state. The strong e-e correlation, a carrier density of 0.5 and the lattice frustration are the key ingredients for creating the spin singlets (PEC state) in strong electron systems such as the organic superconductors.
