Theoretical investigation of the quasiparticle dispersion of bilayer high-Tc superconductors

The renormalization of quasiparticle (QP) dispersion in bilayer high-Tc cuprates is investigated theoretically by examining, respectively, the interactions of the QP with spin fluctuations and phonons. It is illustrated that both interactions are able to give rise to a kink in the dispersion around the antinodes [near (π,0)]. However, remarkable differences between the two cases are found for the peak/dip/hump structure in the line shape, the QP weight, and the interlayer coupling effect on the kink, which are suggested to serve as a discriminance to single out the dominant interaction in the superconducting state. A comparison to recent photoemission experiments shows clearly that the coupling to the spin resonance is dominant for the QP around antinodes in bilayer systems. © 2005 The American Physical Society.published_or_final_versio