Transport studies of metallic La(1-x)A(x)CoO(3) (A = Sr, Ba) ferromagnet

Well below T-C, both resistivity (p) and thermopower (S) of La(1-x)A(x)CoO(3) (A = Sr, Ca, Ba) exhibit T-2 behavior while just below T-C, they show T-4 dependence due to the scattering of charge carriers by magnetic fluctuations. This T-4 dependence of rho close to Tc-C can be suppressed by a magnetic field, leading to a negative bulk magnetoresistance in cobaltates and in other itinerant ferromagnets such as manganites and CrO2. The role of ionic size on T4 dependence of p and S has also been studied. A phase diagram has been constructed for La1-xBaxCoO3 system. (c) 2005 Elsevier B.V. All rights reserved