Specific-heat evidence for strong electron correlations in the thermoelectric material (Na,Ca)Co2O4
Year: 1999
Type: article
Abstract: The specific heat of $(\mathrm{N}\mathrm{a},\mathrm{C}\mathrm{a}){\mathrm{Co}}_{2}{\mathrm{O}}_{4}$ is measured at low-temperatures to determine the magnitude of the electronic specific-heat coefficient $\ensuremath{\gamma},$ in an attempt to gain an insight into the origin of the unusually large thermoelectric power of this compound. It is found that $\ensuremath{\gamma}$ is as large as $\ensuremath{\sim}48 {\mathrm{m}\mathrm{J}/\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{K}}^{2},$ which is an order of magnitude larger than $\ensuremath{\gamma}$ of simple metals. This indicates that $(\mathrm{N}\mathrm{a},\mathrm{C}\mathrm{a}){\mathrm{Co}}_{2}{\mathrm{O}}_{4}$ is a strongly-correlated electron system, where the strong correlation probably comes from the low-dimensionality and the frustrated spin structure. We discuss how the large thermopower and its dependence on Ca doping can be understood with the strong electron correlations.
Authors: Yoichi Ando, N. Miyamoto, Kouji Segawa, T. Kawata, I. Terasaki
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2009565403