Dimensional crossover of charge density wave and thermoelectric properties in CeTe2-xSbx single crystals

Abstract

We have measured the electrical resistivity and Seebeck coefficient of CeTe2-xSbx (x = 0.0, 0.05, 0.1, 0.25, and 0.5) single crystals from 100 K to 300 K along the ab-plane, and we calculated their electronic structures and Fermi surfaces by using the density functional theory approach. The band structures of CeTe2 show the 2-dimensional (2D) Fermi surface nesting behavior, which induce the charge density wave (CDW). In addition, there is a 3-dimensional (3D) electron Fermi surface hindering the perfect CDW gap opening. By hole doping with the substitution of Sb at the Te-site, the 3D-like Fermi surface disappears and the 2D perfect CDW gap opening enhances the power factor up to x = 0.1. With further hole doping, the Fermi surfaces become 3-dimensional structure with heavy hole bands. The enhancement of the power factor is observed near the dimensional crossover of CDW, at x = 0.1, where the CDW gap is maximized. Here we show the strong relationship between the dimensionality of CDW and high thermoelectric power factor. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4756911]