Similarities between Cu and Pu containing high Tc superconductors

PuCoGa5 has with 18.5 K an extremely high T-c for superconductivity compared with other actinide materials having T(c)s around 23 3 K. It appears to be a high T-c superconductor in the field of actinides. After nearly 20 years of research in high T-c superconductors, only Cu containing materials have T(c)s above about 30 K (exception MgB2). BCS theory cannot explain such high transition temperatures, thus other or additional coupling mechanisms like magnetic exchange are necessary. Mixed valence, spin holes in an antiferromagnetic lattice, small energy difference between the various valences and two-dimensionality are common features of Cu and Pu containing superconductors. It can be shown in this paper that the mechanism for superconductivity is the same for Cu and Pu containing materials. (c) 2006 Elsevier B.V. All rights reserved.