Permanent-magnet-based transverse thermoelectric generator with high fill factor driven by anomalous Nernst effect

A transverse thermoelectric generator for magnetic-field-free and high-density power generation utilizing the anomalous Nernst effect is constructed and its performance is characterized. By alternately stacking two different permanent magnets with the large coercivity and anomalous Nernst coefficients of opposite sign, transverse thermoelectric voltage and power can be generated in the absence of external magnetic fields and enhanced owing to a thermopile structure without useless electrode layers. In this study, we construct a bulk module consisting of 12 pairs of SmCo5- and Nd2Fe14B-type permanent magnets having positive and negative anomalous Nernst coefficients, respectively, whose fill factor reaches ∼80%. We demonstrate magnetic-field-free anomalous Nernst power generation up to 177 µW at a temperature difference of 75 K around room temperature, which corresponds to the largest anomalous Nernst power density.