The spin-entropy enhancement induced by Ce doping in Ca3Co4O9+δ
National Laboratory of Solid State Microstructures and Physics Department of Nanjing University Nanjing 210093, China
2 College of Physics and Technology, Guangxi Normal University - Guilin 541004, China
3 College of Science, Zhongyuan University of Technology - Zhengzhou 450007, China
Accepted: 16 June 2010
We present measurements of the thermopower as a function of temperature under different magnetic fields, for Ce-doped Ca3Co4O9+δ. A strong magnetic-field suppression of the thermopower indicates a large spin-entropy contribution. The magnetothermopower is enhanced in all doped samples, which provides an experimental evidence for the enhanced spin entropy by Ce doping. Our magnetic results allow us to determine the decrease in Co4+ concentration which results in the spin-entropy enhancement. We adopt a suitable theoretical model to explain our experimental observations. This investigation gives strong evidence that the enhanced thermopower mainly originates from enhancement of the spin entropy.
PACS: 72.20.Pa – Thermoelectric and thermomagnetic effects / 72.80.Ga – Transition-metal compounds
© EPLA, 2010