CHARACTERISTIC FEATURES OF THE EXOTIC SUPERCONDUCTORS: EVIDENCE FOR A COMMON PAIRING MECHANISM

Abstract

We report on a comprehensive examination of the exotic superconductors (the materials so-labelled by Uemura and co-workers), to determine as far as possible the true systematics among their many anomalous features. In the crystal-chemistry aspects as well as in the electronic properties, we find features which appear to be universal for these materials, and also features which are clearly not universal but which are common enough to be considered typical for these materials. A number of implications are presented. There is strong evidence that all of these materials are sharing some "new" pairing mechanism, usually in addition to the conventional phonon mechanism.