Thermoelectric properties of iron-based superconductors and parent compounds

TL;DR

This review synthesizes experimental data on thermoelectric properties of iron-based superconductors and their parent compounds, revealing insights into their electronic structure, magnetic interactions, and superconducting mechanisms.

Contribution

It provides a comprehensive analysis of thermoelectric effects, including Seebeck and Nernst effects, linking them to underlying physical phenomena in iron-based superconductors.

Findings

Nernst effect enhancement relates to Dirac cone bands and multiband transport.

Thermoelectric behavior indicates Fermi surface reconstruction and Lifshitz transitions.

Superconducting fluctuations contribute to large Nernst signals in the normal state.

Abstract

Herewith, we review the available experimental data of thermoelectric transport properties of iron-based superconductors and parent compounds. We discuss possible physical mechanisms into play in determining the Seebeck effect, from whence one can extract information about Fermi surface reconstruction and Lifshitz transitions, multiband character, coupling of charge carriers with spin excitations and its relevance in the unconventional superconducting pairing mechanism, nematicity, quantum critical fluctuations close to the optimal doping for superconductivity, correlation. Additional information is obtained from the analysis of the Nernst effect, whose enhancement in parent compounds must be related partially to multiband transport and low Fermi level, but mainly to the presence of Dirac cone bands at the Fermi level. In the superconducting compounds, large Nernst effect in the normal state is explained in terms of fluctuating precursors of the spin density wave state, while in the superconducting state it mirrors the usual vortex liquid dissipative regime. A comparison between the phenomenology of thermoelectric behavior of different families of iron-based superconductors and parent compounds allows to evidence the key differences and analogies, thus providing clues on the rich and complex physics of these fascinating unconventional superconductors.