Effect of the Pseudogap on the Quasiparticle Transport from the Static Limit to Finite Energy for Cuprate Superconductors

Within the renormalized t ‐ J model and self‐consistent mean field theory, the doping and energy dependences of the quasiparticle transport is studied in cuprate superconductors, especially in the underdoped region. By calculating the doping and energy dependence of the ratio of the thermal conductivity to the electrical conductivity at temperature T ,κ ( ω ) / σ ( ω ) T(the form of the Wiedemann–Franz law), it is shown thatκ ( ω ) / σ ( ω ) Tincreases with the increase of energy from underdoping to overdoping, whereas it is constant in heavily overdoped cuprate superconductors and recovers the result of the Wiedemann–Franz law at zero energy. The slope ofκ ( ω ) / σ ( ω ) Tis the highest in the underdoped region, decreases with increasing the doping concentration in the whole doping range, and reaches zero in the heavily overdoped region. In particular, the ratioκ ( ω ) / σ ( ω ) Tas a function of energy exhibits a characteristic peak over the transition from underdoping to overdoping, and the position of the characteristic peak ω WF decreases monotonically upon increasing doping concentration. Therefore, these results indicate that the slope ofκ ( ω ) / σ ( ω ) Tand characteristic peaks as a function of doping are related to the appearance of the pseudogap in cuprate superconductors.