Fresh from the Oven

Abstract --- The electron and phonon transports in CaMnO₃ and in one of its Bi-doped counterparts, namely, Bi_0.03Ca_0.97MnO ₃, are investigated using the thermoelectric transport measurements and first-principles calculations.We find that antiferromagnetic insulator CaMnO3 breaks the Wiedemann–Franz law with the Lorenz number reaching four times that of ordinary metals at room temperature. Bismuth doping reduces both the electrical resistivity and Seebeck coefficient of CaMnO3; thus, it recovers the Wiedemann–Franz law behavior. In addition, Bi_0.03Ca_0.97 MnO₃ possesses a shorter phonon lifetime according to the transport measurements. As a result, Bi_0.03Ca_0.97MnO₃ exhibits superior thermoelectric properties over pristine CaMnO₃ owing to the lower thermal conductivity and electrical resistivity.