Mott transition, antiferromagnetism, and unconventional superconductivity in layered organic superconductors
Résumé
The pressure vs temperature phase diagram of the layered organic superconducting family κ-(BEDT-TTF)2X is accurately determined by investigating the NMR and AC susceptibility properties of the anion substituted compound X=Cu[N(CN)2]Cl under helium gas pressure. A first order boundary between antiferromagnetism and superconductivity is established which is found to evolve into a first order metal–insulator transition line in the paramagnetic domain. This latter transition line is in turn ending in a critical point above which a mere crossover is retrieved. The whole phase diagram features a point-like region at which metallic, insulating, antiferromagnetic and unconventional superconducting phases all meet.