Electronic structure and thermoelectric power of cerium compounds at high pressure

The normal and high pressure thermoelectric power (TEP) of three cerium compounds are compared and the origin of the differences in their behaviour is discussed. CePd ₃ shows a monotonic increase in thermopower as a function of pressure up to maximum pressure studied ∼5 GPa. In sharp contrast, CeSn ₃ shows an increase only up to 2-3 GPa and then starts decreasing. The ambient and high pressure behaviour is discussed by computing electronic structures of three Ce compounds, viz. CePd ₃, CeSn ₃ and CeIn ₃ using TB-LMTO method. The f-band width is larger in CeIn ₃ as compared to the other two compounds, explaining the cause for its lower ambient TEP. The density of states of the f-band is maximum, narrower and the closest to the Fermi level in CePd ₃ explaining its highest TEP. The band structure does not show much variation at higher compressions for CePd ₃ and CeIn ₃. However, in the case of CeSn ₃, the band structure at higher compressions indicates an electronic topological transition, a possible cause for the pronounced peak TEP, observed in experiment.