Effect of local magnetic moments on spectral properties and resistivity near interaction- and doping-induced Mott transitions

We study the effect of the formation and screening of local magnetic moments on the temperature and interaction dependences of spectral functions and resistivity in the vicinity of the metal-insulator transition. We use dynamical mean-field theory for the strongly correlated Hubbard model and associate the peculiarities of the above-mentioned properties with those found for the local charge.c and spin.s susceptibilities. We show that at half filling the maximum of resistivity at a certain temperature T * corresponds to the appearance of a central quasiparticle peak of the spectral function and entering the metallic regime with well-defined fermionic quasiparticles. At the same time, the temperature of the crossover to the regime with screening of local magnetic moments, determined by the minimum of double occupation, is smaller than the temperature scale T * and coincides at half filling with the boundary T ss=1(U) corresponding to the exponent of resistivity ss = d ln./d ln T = 1. Away from half filling we find a weak increase of the temperature of the beginning and completion of the screening (i.e., Kondo temperature) of local magnetic moments, while the unscreened local magnetic moments exist only up to a few percent of doping. In the low-temperature regime T < T ss=1 the simultaneous presence of itinerant and localized degrees of freedom yields an almost linear temperature dependence of the scattering rate and resistivity.