Magnetoresistance in ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{CoO}}_3$ for 0.05⩽x⩽0.25

The dc resistivity, magnetoresistance, and magnetic susceptibility of ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{CoO}}_3$ compounds have been investigated in the temperature range of 4–300 K for magnetic fields up to 7 T. In the doping range studied (0.05≤x≤0.25) the electronic properties of the material exhibit a crossover from semiconducting to metallic behavior. The magnetoresistance is highest in the semiconducting state. A correlation was found between the energy gap determined from the dc conductivity and the energy scale identified from neutron scattering data. The results are interpreted in terms of a double-exchange model. © 1996 The American Physical Society.