Enhancement of the spin entropy in NaxCo2O4 by Ni doping

Tang, Guodong; Teng Yang; Xiaonong Xu; Chipui Tang; Li Qiu; Zhidong Zhang; Liya Lv; Zhihe Wang; Youwei Du
July 2010
Applied Physics Letters;7/19/2010, Vol. 97 Issue 3, p032108
Academic Journal
The effects of Ni doping on the spin entropy in NaxCo2O4 (x=1.2) has been carefully studied. A strong magnetic-field suppression of the thermopower indicates the emergence of large spin-entropy effect. The magnetothermopower increases with increasing Ni doping level, suggesting that Ni doping improves the spin entropy of NaxCo2O4. Based on analysis of x-ray absorption spectra, we propose a spin-entropy competition mechanism to explain well the spin-entropy enhancement.


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