The spin-entropy enhancement induced by Ce doping in Ca3Co4O9+δ

G. D. Tang; X. N. Xu; C. P. Tang; Z. H. Wang; Y. He; L. Qiu; L. Y. Lv; L. Xing; Y. W. Du

doi:10.1209/0295-5075/91/17002

All issues

Volume 91 / No 1 (July 2010)

EPL, 91 1 (2010) 17002

Abstract

Issue		EPL Volume 91, Number 1, July 2010


Article Number		17002
Number of page(s)		5
Section		Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI		https://doi.org/10.1209/0295-5075/91/17002
Published online		16 July 2010

EPL, 91 (2010) 17002

The spin-entropy enhancement induced by Ce doping in Ca₃Co₄O_9+δ

G. D. Tang¹, X. N. Xu¹, C. P. Tang¹, Z. H. Wang¹^a, Y. He², L. Qiu¹, L. Y. Lv¹, L. Xing³ and Y. W. Du¹

¹ 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

^a zhwang@nju.edu.cn

Received: 9 March 2010
Accepted: 16 June 2010

Abstract

We present measurements of the thermopower as a function of temperature under different magnetic fields, for Ce-doped Ca₃Co₄O_9+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

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