Superconductivity from orbital nematic fluctuations

TL;DR

This paper investigates how orbital nematic fluctuations can induce strong-coupling superconductivity in iron pnictides, showing that intra-pocket fluctuations are key and coexist with nematic order.

Contribution

It demonstrates that low-energy nematic fluctuations within pockets can produce high transition temperatures, highlighting a mechanism for superconductivity beyond magnetic fluctuations.

Findings

Nematic fluctuations within pockets lead to strong-coupling superconductivity.

Transition temperatures are comparable to those in real pnictides.

Superconducting and nematic states coexist over a large phase diagram region.

Abstract

Recent experiments suggest that besides of antiferromagnetic fluctuations nematic fluctuations may contribute to the occurrence of superconductivity in iron pnictides. Motivated by this observation we study superconductivity from nematic fluctuations in a minimal two-band model. The employed band parameters are appropriate for iron pnictides and lead to four pockets for the Fermi line. It is shown that low-energy, long-wavelength nematic fluctuations within the pockets give rise to strong-coupling superconductivity whereas the large momenta density fluctuations between pockets are rather irrelevant. The obtained transition temperatures are similar to those typically found in the pnictides and are rather robust against repulsive Coulomb interactions. The superconducting and nematic states coexist in a large region of the phase diagram.