Transport properties of L(1-x)Sr(x)MnO(3) (L=Pr, Nd; 1/4<=x<=1/2)

We report on the temperature dependence of the zero-field resistivity (rho), absolute thermopower (S) and the room temperature lattice constants of the title materials. The results indicate that at high temperatures, above the transition to the ferromagnetic (FM) state electronic transport is carried out in narrow bands. An attempt to account for the measured values of S was put forward. Evidence for the presence of a gap in the density of states of the compounds with x similar to 1/4, possibly due to Coulomb repulsion, was found in S(T) at temperatures far above T-c. The positive sign of S found in the FM state of most of the compounds studied is consistent with transport in a one-electron band with polarized states. The temperature dependence of the resistivity in the FM stale is consistent with a transition probability which depends exponentially on the transfer integral.