Thermoelectric and transport properties of CeBiPt and LaBiPt

Abstract

The electrical resistivity ρ, Hall coefficient RH, thermoelectric power S, and thermal conductivity κ have been measured on an antiferromagnet CeBiPt (TN=1 K) and the nonmagnetic analogue LaBiPt, which crystallize in the cubic MgAgAs-type structure. The large values |RH|∼1 cm3/C and ρ∼1.2 mΩ cm at 300 K indicate that both compounds are low-carrier concentration semimetals. The strong temperature dependences of ρ, S, and RH for CeBiPt contrast with the weak temperature dependences for LaBiPt. For CeBiPt, S(T) has a positive maximum of 120 μV/K at 100 K. However, the sign of RH(T) changes from positive to negative with increasing temperature at 170 K, above which S(T) of CeBiPt becomes smaller than LaBiPt. These observations suggest strong dependence of mobility for hole and electron carriers in CeBiPt. In this system, κ(T) is dominated by the phonon contribution, which is consistent with a small carrier concentration. Furthermore, the combination of S, ρ, and κ allows us to estimate the figure of merit for thermoelectric application, Z=1.7×10−4 K−1 at 75 K for CeBiPt.