Publication details

Microscopic gauge-invariant theory of the c-axis infrared response of bilayer cuprate superconductors and the origin of the superconductivity-induced absorption bands



Year of publication 2009
Type Article in Periodical
Magazine / Source Physical Review B
MU Faculty or unit

Faculty of Science

Field Solid matter physics and magnetism
Keywords bilayer cuprate superconductors; c-axis infrared response; spin-fermion model; vertex corrections; gauge-invariance
Description We report on results of our study of the c-axis infrared conductivity of bilayer high-Tc cuprate superconductors using a model involving the bilayer-split bands. An emphasis is on the gauge invariance of the theory, which turns out to be essential for the understanding of the electrodynamics of these compounds. The description of the optical response involves local intra- bilayer and interbilayer current densities and local conductivities. The local conductivities are obtained using a microscopic theory, where the quasiparticles of the two bands are coupled to spin fluctuations. The resulting response of the model is studied in detail and an interpretation of two superconductivity-induced peaks in the experimental data of the real part of the c-axis conductivity is proposed. The peak around 400 cm-1 is attributed to a collective mode of the intrabilayer regions, which is an analog of the Bogolyubov-Anderson mode. The peak around 1000 cm-1 is interpreted as a pair-breaking feature.
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