Finite-temperature conductivity in the planar t-J model

Results are for finite-temperature optical conductivity σ(ω) and dc resistivity ρ(T), obtained within the t-J model on a square lattice by a method based on the Lanczos diagonalization. Studying systems with N=16 or 18 sites and hole concentrations ${\mathit{c}}_{\mathit{h}}$≤0.25, a thermodynamic behavior is reached for quite low temperatures. σ(ω) spectra reveal a slow non-Drude falloff at large frequencies and the emergence of a broad midinfrared peak at low doping. At optimum doping ρ(T) shows nearly linear variation with T. Both quantities agree well with experimental results in cuprates.