Thermoelectric Response Driven by Spin-State Transition in La1−xCexCoO3 Perovskites

Abstract

An unusual thermoelectric response was observed in n-type perovskite oxide La1−xCexCoO3. Combining transport and magnetic measurements, we found that the thermoelectric response is driven by the spin-state transition of Co3+. This transition destroys the spin blockade effect and induces an abrupt decrease of resistivity as well as an insulator−metal transition. In contrast to the resistivity change, changes in thermopower and thermal conductivity are moderate. Consequently, a peak of figure of the merit ZT is present in a narrow temperature range. The room-temperature ZT ≈ 0.018 of La0.94Ce0.06CoO3 is comparable to that of p-type NaxCoO2. These observations can be helpful for the search and design of new thermoelectric materials.