Electronic spectra of optimal doped bilayer and trilayer high-Tc cuprate superconductors

We present the calculation of the electronic spectral function and density of states in the optimal and overdoped bilayer and trilayer cuprates (like Bi2Sr2CaCu2O8+x and Bi2Sr2Ca2Cu3O10+x) as a function of interlayer coupling in d-wave superconducting state. We have used the multilayer tight binding attractive Hubbard Hamiltonian containing the momentum dependent interlayer coupling parameter to obtain the expressions of single particle spectral function and density of states within BCS-mean-field Green's function equations of motion approach for bilayer and trilayer superconducting cuprates. On the basis of numerical computation, it has been found that the coupling between the cuprates plane within the unit cell is responsible for the splitting of bonding and antibonding bands in the electronic spectral function at (π, 0) point of Brillouin zone for optimal doped bilayer cuprates, while a trilayer splitting in the spectral function at (π, 0) point is pointed out in the form of bonding, non-bonding and antibonding bands in optimal doped trilayer cuprates in superconducting state. These findings are in qualitative agreement with the recent photoemission spectroscopic measurements in superconducting bilayer and trilayer cuprates. We have also computed numerically the density of states in optimal and overdoped bilayer and trilayer cuprates in the superconducting state and predicted the splitting of coherence peak in the density of states as a manifestation of bilayer and trilayer couplings. The variation of density of states found to be in agreement with the recent tunneling measurements in multilayered cuprates in superconducting state.