An impurity resistivity of doped manganese perovskites

We present a two-time of relaxation approach at an analysis of a magnetoresistance in ferromagnetic manganese perovskites La1-x(Ca,Sr)(x)MnO. To explain a change in the low-held response from predominantly quadratic dR/dH\(H-->0) = 0 for T > T-c to linear dR/dH\(H-->0) for T < T-c as noted in the measurements in thin films La0.7Ca0.3MnO3 we calculated held and temperature dependences of a impurity contribution to a carrier mobility in a framework of the 2p(O)- and 3d(Mn)-scattering model elaborated for manganese perovskites. We obtained the field-dependent impurity contribution to the overall scattering of carriers that show a transition in the low-field (H) dependence of R from quadratic above T-c to linear below consistent with an experiment. The calculated negative magnetoresistance ratio is sharply peaked at a temperature-near T-c or below. (C) 1999 Elsevier Science B.V. All rights reserved.