Corrugated flat band as an origin of large thermopower in hole doped PtSb$_2$

TL;DR

This paper explains the large thermopower in hole-doped PtSb$_2$ as arising from a unique corrugated flat band structure, which enhances thermoelectric properties by balancing Seebeck coefficient and conductivity.

Contribution

It introduces a first-principles based model revealing the corrugated flat band as the origin of high thermopower in PtSb$_2$, connecting band structure to thermoelectric performance.

Findings

The valence band in PtSb$_2$ has a flat, corrugated shape.

The model's Seebeck coefficient matches experimental data.

Large thermopower is due to the corrugated flat band structure.

Abstract

The origin of the recently discovered large thermopower in hole-doped PtSb$_2$ is theoretically analyzed based on a model constructed from first principles band calculation. It is found that the valence band dispersion has an overall flatness combined with some local ups and downs, which gives small Fermi surfaces scattered over the entire Brillouin zone. The Seebeck coefficient is calculated using this model, which gives good agreement with the experiment. We conclude that the good thermoelectric property originates from this "corrugated flat band", where the coexistence of large Seebeck coefficient and large electric conductivity is generally expected.