Key points are not available for this paper at this time.
Muon-spin-relaxation and bulk measurements of the magnetic-field penetration depth suggest that the cuprate high-T₂, bismuthate, organic Chevrel-phase, and heavy-fermion systems possibly belong to a unique group of superconductors characterized by high transition temperatures T₂ relative to the values of nₒ/m^* (carrier density/effective mass). This feature distinguishes these exotic superconductors from ordinary BCS superconductors.
Uemura et al. (Mon,) studied this question.