Quantum critical fluctuations in an Fe-based superconductor

TL;DR

This study demonstrates that quantum critical fluctuations influence the electronic properties of an Fe-based superconductor, linking quantum criticality with the emergence of high-temperature superconductivity.

Contribution

It provides experimental evidence of quantum critical scaling in an Fe-based superconductor and connects quantum fluctuations with superconducting behavior.

Findings

Presence of marginal Fermi liquid scaling in inelastic light scattering data.

Distinction between quantum critical and classical critical regions based on doping.

Overlap of high Tc regions with quantum critical scaling indicating quantum fluctuations' role in superconductivity.

Abstract

Quantum critical fluctuations may prove to play an instrumental role in the formation of unconventional superconductivity. Here, we show that the characteristic scaling of a marginal Fermi liquid is present in inelastic light scattering data of an Fe-based superconductor tuned through a quantum critical point (QCP) by chemical substitution or doping. From the doping dependence of the imaginary time dynamics we are able to distinguish regions dominated by quantum critical behavior from those having classical critical responses. This dichotomy reveals a connection between the marginal Fermi liquid behavior and quantum criticality. In particular, the overlap between regions of high superconducting transition temperatures and quantum critical scaling suggests a contribution from quantum fluctuations to the formation of superconductivity.