Variation of shear moduli across superconducting phase transitions

TL;DR

This paper investigates how shear moduli vary across superconducting transitions, revealing small changes generally, but significant boosts in Fe-based and A15 systems due to enhanced nematic correlations, explained through a microscopic theory.

Contribution

The study provides a microscopic explanation for the large shear modulus changes in certain superconductors linked to nematic correlations, which was not previously understood.

Findings

Most superconductors show small shear modulus changes across transitions.

Fe-based and A15 systems exhibit five orders of magnitude increase in shear moduli change.

Enhanced nematic correlations cause the boost in shear modulus variation.

Abstract

We study how shear moduli of a correlated metal change across superconducting phase transitions. Using a microscopic theory we explain why for most classes of superconductors this change is small. The Fe-based and the A15 systems are notable exceptions where the change is boosted by five orders of magnitude. We show that this boost is a consequence of enhanced nematic correlation. The theory explains the unusual temperature dependence of the orthorhombic shear and the back-bending of the nematic transition line in the superconducting phase of the Fe-based systems.