C-AXIS CHARGE DYNAMICS IN THE BILAYER T-J MODEL - A NUMERICAL STUDY

We report a numerical study of a bilayer t-J model, i.e., two layers of the two-dimensional t-J model weakly coupled by hopping and exchange terms and present results for the single-particle spectral function, and the optical conductivity for in-plane and out-of-plane current. The results indicate renormalized free particle behavior in the z direction, i.e., the effective z-axis hopping integral is renormalized by the in-plane quasiparticle weight. The spectral weight of the z-axis conductivity is concentrated in a dominant low-energy peak, the current correlation function can be obtained from the convolution of the single-particle Green function. © 1995 The American Physical Society.