Unified picture for the colossal thermopower compound FeSb$_2$

TL;DR

This paper explains the giant thermopower in FeSb$_2$ as a phonon-drag effect linked to excess iron-induced in-gap states, providing a comprehensive model of its transport properties.

Contribution

It reveals the phonon-drag mechanism as the origin of FeSb$_2$'s colossal thermopower and models its transport coefficients accurately.

Findings

Identifies excess iron as the source of in-gap states.

Demonstrates phonon-drag as the key mechanism.

Provides a unified explanation for response function features.

Abstract

We identify the driving mechanism of the gigantic Seebeck coefficient in FeSb$_2$ as the phonon-drag effect associated with an in-gap density of states that we demonstrate to derive from excess iron. We accurately model electronic and thermoelectric transport coefficients and explain the so far ill-understood correlation of maxima and inflection points in different response functions. Our scenario has far-reaching consequences for attempts to harvest the spectacular powerfactor of FeSb$_2$.