Energy-gap structure of a t-J bilayer

The role of interlayer coupling in copper-oxide superconductors represents an open problem in high-T-c superconductivity. In this work, the energy gap and the density of states of a t-J bilayer are analyzed for different value of the doping S within a mean-field approximation. It is shown that an interlayer single-electron hopping increases the ratio R=2 Delta/KTc and that the extent of such increase depends strongly on the doping delta. The density of states contains both BCS-like and logarithmic singularities and presents a multiple-peak structure, in qualitative agreement with recent tunneling experiments.