Podrobný výpis o publikaci

The nature of the electronic coupling between the neighbouring copper-oxygen planes in bilayer high-Tc cuprate superconductors is closely related to that of the underlying ground state. For this reason, it is of fundamental interest. Photoemission experiments on bilayer Bi-2212 reveal two well defined bands, corresponding to even- and odd- symmetry electronic states of the two planes. Measured c-axis IR spectra of underdoped bilayer materials, however, rather appear to be consistent with the model, where the stack of the planes is represented by a superlattice of Josephson junctions. We report on our attempts to resolve the controversy by computing the IR response considering the bilayer-split bands, such as observed by photoemission, and comparing the results with optical data. The simplest conceivable approach has been improved by including selfenergy terms, such as used in our study of the in-plane response, and vertex-corrections required for the theory to be gauge invariant.