Spin-entropy origin and scaling behavior of the thermopower of LaBaCoO

We report a detailed investigation of the thermopower and magnetic properties of La0.95 Ba0.05CoO3. The large negative magnetothermopower is found to scale with both magnetic field and temperature, indicating a spin-entropy contribution to the thermpower. We formulate a new general expression to describe the thermopower from spin entropy with spin-interaction considered. The scaling behaviour is analyzed in a theoretical model, which provides a satisfactory description of the observed data. The magnetic results further support our analysis. This investigation shows that spin entropy plays a substantial role in the thermopower.