FINITE-TEMPERATURE CONDUCTIVITY IN THE PLANAR T-J MODEL

Results are for finite-temperature optical conductivity sigma(omega) a nd dc resistivity rho(T), obtained within the t-J model on a square la ttice by a method based on the Lanczos diagonalization. Studying syste ms with N = 16 or 18 sites and hole concentrations c(h) less-than-or-e qual-to 0.25, a thermodynamic behavior is reached for quite low temper atures. Sigma(omega) spectra reveal a slow non-Drude falloff at large frequencies and the emergence of a broad midinfrared peak at low dopin g. At optimum doping rho(T) shows nearly linear variation with T. Both quantities agree well with experimental results in cuprates.