Negative Thermoelectric Power Induced by Positive Carriers in CaMn_3−xCu_xMn₄O₁₂

Abstract

We have found that the thermoelectric power of the ordered perovskite CaMn_3−xCu_xMn₄O₁₂ is negative at high temperature (−35 μV/K at 1000 K), although this material is a hole-doped conductor in which Cu²⁺ is substituted for Mn³⁺. This is quantitatively explained by the extended Heikes formula, where entropy flows in a direction opposite to the charge.