Thermopower and thermal conductivity of superconducting perovskite MgCNi3 -: art. no. 064534

The thermopower and thermal conductivity of superconducting perovskite MgCNi3(T(c)approximate to8 K) have been studied. The thermopower is negative from room temperature to 10 K. Combined with the negative Hall coefficient reported previously, the negative thermopower definitely indicates that the carrier in MgCNi3 is electron type. The nonlinear temperature dependence of thermopower below 150 K is explained by the electron-phonon interaction renormalization effects. The thermal conductivity is of the order for intermetallics, larger than that of borocarbides, and smaller than MgB2. In the normal state, the electronic contribution to the total thermal conductivity is slightly larger than the lattice contribution. The transverse magnetoresistance of MgCNi3 is also measured. It is found that the classical Kohler's rule is valid above 50 K. An electronic crossover occurs at T* similar to 50 K, resulting in the abnormal behavior of resistivity, thermopower, and magnetoresistance below 50 K.