Thermoelectric and transport properties of CeBiPt and LaBiPt

The electrical resistivity rho, Hall coefficient R-H, thermoelectric power S, and thermal conductivity kappa have been measured on an antiferromagnet CeBiPt (T-N = 1 K) and the nonmagnetic analogue LaBiPt, which crystallize i n the cubic MgAgAs-type structure. The large values \R-H\ similar to 1 cm(3 )/C and rho similar to 1.2 m Ohm cm at 300 K indicate that both compounds a re low-carrier concentration semimetals. The strong temperature dependences of rho, S, and R-H for CeBiPt contrast with the weak temperature dependenc es for LaBiPt. For CeBiPt, S(T) has a positive maximum of 120 muV/K at 100 K. However, the sign of R-H(T) changes from positive to negative with incre asing 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, kappa (T) is dominated by the phonon contribution, which is consistent with a small carrier concentra tion. Furthermore, the combination of S, rho, and kappa allows us to estima te the figure of merit for thermoelectric application, Z = 1.7 x 10(-4) K-1 at 75 K for CeBiPt. (C) 2001 American Institute of Physics.