Finite-temperature properties of the two-dimensional Kondo lattice model

Using the recently developed Lanczos technique we study finite-temperature properties of the 2D Kondo lattice model at various fillings of the conduction band. At half filling the quasiparticle gap governs physical properties of the chemical potential and the charge susceptibility at small temperatures. In the intermediate coupling regime quasiparticle gap scales approximately linearly with the Kondo coupling as ${\ensuremath{\Delta}}_{\mathrm{qp}}\ensuremath{\sim}0.3J.$ Temperature dependence of the spin susceptibility seems to reveal two different temperature scales. A spin gap in the intermediate regime leads to a drop of the spin susceptibility at low temperatures, while a scaling of spin susceptibility is found for temperatures above ${T}_{c}>~0.6J.$ Charge susceptibility at finite doping reveals existence of heavy quasiparticles. A low energy scale is found at finite doping.