Discovery of colossal Seebeck effect in metallic Cu<sub>2</sub>Se.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30622265.
- Also identified by DOI 10.1038/s41467-018-07877-5 and PMC identifier 6325113.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Both electrical conductivity σ and Seebeck coefficient S are functions of carrier concentration being correlated with each other, and the value of power factor S<sup>2</sup>σ is generally limited to less than 0.01 W m<sup>-1</sup> K<sup>-2</sup>. Here we report that, under the temperature gradient applied simultaneously to both parallel and perpendicular directions of measurement, a metallic copper selenide, Cu<sub>2</sub>Se, shows two sign reversals and colossal values of S exceeding ±2 mV K<sup>-1</sup> in a narrow temperature range, 340 K < T < 400 K, where a structure phase transition takes place. The metallic behavior of σ possessing larger magnitude exceeding 600 S cm<sup>-1</sup> leads to a colossal value of S<sup>2</sup>σ = 2.3 W m<sup>-1</sup> K<sup>-2</sup>. The small thermal conductivity less than 2 W m<sup>-1</sup> K<sup>-1</sup> results in a huge dimensionless figure of merit exceeding 400. This unusual behavior is brought about by the self-tuning carrier concentration effect in the low-temperature phase assisted by the high-temperature phase.