Basic similarities among cuprate, bismuthate, organic, Chevrel-phase, and heavy-fermion superconductors shown by penetration-depth measurements

Muon-spin-relaxation and bulk measurements of the magnetic-field penetration depth suggest that the cuprate high-Tc, bismuthate, organic Chevrel-phase, and heavy-fermion systems possibly belong to a unique group of superconductors characterized by high transition temperatures Tc relative to the values of ns/m* (carrier density/effective mass). This feature distinguishes these exotic superconductors from ordinary BCS superconductors.