Specific-heat evidence for strong electron correlations in the thermoelectric material (Na,Ca)Co2O4
Abstract
The specific heat of (Na,Ca)Co2O4 is measured at low-temperatures to determine the magnitude of the electronic specific-heat coefficient γ, in an attempt to gain an insight into the origin of the unusually large thermoelectric power of this compound. It is found that γ is as large as ~48 mJ/molK2, which is an order of magnitude larger than γ of simple metals. This indicates that (Na,Ca)Co2O4 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.
- Publication:
-
Physical Review B
- Pub Date:
- October 1999
- DOI:
- 10.1103/PhysRevB.60.10580
- arXiv:
- arXiv:cond-mat/9907008
- Bibcode:
- 1999PhRvB..6010580A
- Keywords:
-
- 65.40.+g;
- 71.27.+a;
- 71.20.-b;
- 71.20.Be;
- Strongly correlated electron systems;
- heavy fermions;
- Electron density of states and band structure of crystalline solids;
- Transition metals and alloys;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 5 pages, 4 figures, accepted for publication in Phys. Rev. B