Kink Structure in Nodal Quasiparticle Dispersion in a Boson-Fermion Model of Superconductivity

Abstract

At temperatures below a certain T *, single unbound electrons in high-T-c cuprates are assumed to coexist with bosonic Cooper pairs (CPs) of electrons emerging incoherently from an attractively interacting system of fermions. Due to both simultaneous interfermion attractions (as in BCS theory) and depairings, the conductive electrons at temperatures higher than the T-c of a Bose-Einstein condensation of preformed CPs fluctuate unceasingly between single-fermionic states and states of two bound electrons considered actual bosonic objects. We explore how these interactions in a background of such"frustrated electrons," i. e., those electrons appearing both as unbound (free) electrons and as constituents of the bosonic CPs, affect the dispersion of a fermion moving in the assembly of other electrons and, in particular, how the recently observed "kinks" in the dispersion curves emerge.