Thermal and electronic transport properties of CeTe_2-xSn _x compounds

The thermal and electronic transport properties on rare-earth dichalcogenide compounds of CeTe_2-x Sn_x (x0.1) were investigated by measuring electrical resistivity ρ, thermal conductivity κ, and Seebeck coefficient S. Compound of CeTe2 exhibited very low κ (1.25 W m-1 K-1) at 300 K, which was understood by the charge density wave lattice distortion. From the ρ (T) measurements, the metallic property of CeTe2 was significantly enhanced by Sn substitution. The temperature-dependent behavior of S (T) for CeTe_2-x Sn_x (x=0.05 and 0.1) was well described by the inelastic Umklapp process and the phonon drag. The low Seebeck coefficient of CeTe2 (S≈2.5 μV/K at T≈300 K) was increased by Sn doping. From the band structure calculation, the semimetallic band character of CeTe2 was revealed with symmetric electron-hole band dispersion near the Fermi level. The symmetric electron-hole band dispersion of CeTe2 is responsible for the low Seebeck coefficient. The enhancement of the metallic property and Seebeck coefficient because of Sn substitution could be understood by the charge imbalance between electrons and holes caused by hole doping in the Te monolayer.