Large thermopower in novel thermoelectric Yb(Si1−xGex)2 induced by valence fluctuation

• DOI: 10.1063/5.0092002
• Publication Date: 2022-08-09T14:38:15Z
• Authors: Akinori Nishide; Sora-at Tanusilp; Wataru Kowa; Mitsuharu Yashima; Akira Nambu; Jun Hayakawa; Yuji Ohishi; Hiroaki Muta; Hidekazu Mukuda; Ken Kurosaki
• Keywords: Ytterbium

Ytterbium silicide-based thermoelectric materials have attracted attention because they exhibit large power factors owing to absolute values of their Seebeck coefficient as well high electrical conductivity. Here, we demonstrate that, in the Yb(Si1−xGex)2 system, by controlling valence fluctuation, combine two phenomena, namely, Kondo effect and suppression spin fluctuation. This leads a density states fluctuation 4f electrons, thereby resulting with extremely low resistivity. Consequently, Yb(Si0.5Ge0.5)2 exhibits high-power factor 8.4 mW K−2 m−1, which makes energy harvesting from cold source practical possibility.