Analysis of superconductivity in Ba1−xKxBiO3 on the basis of indirect-exchange mediated pairing

Abstract

Analysis of superconductivity in BaC1C-CxKCxBiOC3 on the bais of indirect-exchange mediated pairing Jansen, L.; Block, R.; Stepankin, V. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. AbstractAfter a critical survey of current interpretations of superconductivity in (Ba,K)BiO3, we present a quantitative analysis of this system, with emphasis on dependence of the critical temperature on potassium content and on pressure (external or 'chemical'). Adopting a BCS formalism, Cooper-pair formation is assumed not to be phonon-mediated, but to arise from indirect-exchange interactions between conduction electrons via oxygen anions (oxygen valence band), by analogy with previous analyses of cuprate high-T c superconductors. Numerical calculations are carried through with, and without, accounting for shrinkage of the lattice with increasing potassium content. Results for pressure gradients of T c, at varying doping, and T c under pressures up to 20 GPa, are compared with experimental data. Extension of the analysis to the bismuthate Ba(Pb,Bi)O 3 is outlined.