Comparison of temperature and doping dependence of elastoresistivity near a putative nematic quantum critical point

J C Palmstrom,S T Hannahs,I R Fisher,P Walmsley,J A W Straquadine,D H Burns,M E Sorensen

doi:10.1038/s41467-022-28583-3

Abstract

Strong electronic nematic fluctuations have been discovered near optimal doping for several families of Fe-based superconductors, motivating the search for a possible link between these fluctuations, nematic quantum criticality, and high temperature superconductivity. Here we probe a key prediction of quantum criticality, namely power-law dependence of the associated nematic susceptibility as a function of composition and temperature approaching the compositionally tuned putative quantum critical point. To probe the ‘bare’ quantum critical point requires suppression of the superconducting state, which we achieve by using large magnetic fields, up to 45 T, while performing elastoresistivity measurements to follow the nematic susceptibility. We performed these measurements for the prototypical electron-doped pnictide, Ba(Fe1−xCox)2As2, over a dense comb of dopings. We find that close to the putative quantum critical point, the elastoresistivity appears to obey power-law behavior as a function of composition over almost a decade of variation in composition. Paradoxically, however, we also find that the temperature dependence for compositions close to the critical value cannot be described by a single power law.

Highlights

Strong electronic nematic fluctuations have been discovered near optimal doping for several families of Fe-based superconductors, motivating the search for a possible link between these fluctuations, nematic quantum criticality, and high temperature superconductivity
We focus on nematic fluctuations and the variation of the nematic susceptibility upon approach to the associated putative quantum critical point since this is the first of the two possible quantum critical points that are encountered upon approaching the ordered states from the overdoped regime
For a nematic quantum critical point in a metal, the system is anticipated to be in a regime where d + z > 4, where the effective dimensionality d is already increased due to coupling of the nematic fluctuations to the crystal lattice[13,14]

Summary

Introduction

Strong electronic nematic fluctuations have been discovered near optimal doping for several families of Fe-based superconductors, motivating the search for a possible link between these fluctuations, nematic quantum criticality, and high temperature superconductivity. We probe a key prediction of quantum criticality, namely power-law dependence of the associated nematic susceptibility as a function of composition and temperature approaching the compositionally tuned putative quantum critical point. To date, power-law scaling of neither the magnetic nor nematic susceptibility has been observed as a function of composition, and despite suggestive signatures, the universality of quantum criticality has not been established. It remains an open question for most Fe-based superconductors whether there is avoided criticality[10,11,12], or one or two quantum critical points ‘hidden’ beneath the superconducting dome. Distance from the critical point, both in temperature and in doping, will introduce increasingly large corrections to the power-law scaling

Methods

Results

Conclusion