Robustness of quantum critical pairing against disorder

TL;DR

This paper investigates how disorder affects quantum critical pairing in high-temperature superconductors, revealing a reduced suppression of the transition temperature near magnetic quantum critical points, which explains their robustness.

Contribution

It provides a theoretical analysis showing that quantum critical fluctuations can mitigate the impact of disorder on superconductivity, offering new insights into unconventional pairing mechanisms.

Findings

Disorder has a weaker effect on $T_c$ near quantum critical points.

Quantum fluctuations suppress the spectral weight, influencing pairing.

The suppression rate of $T_c$ is significantly reduced close to magnetic quantum criticality.

Abstract

The remarkable robustness of high-temperature superconductors against disorder remains a controversial obstacle towards the elucidation of their pairing state. Indeed, experiments report a weak suppression rate of the transition temperature $T_{c}$ with disorder, significantly smaller than the universal value predicted by extensions of the conventional theory of dirty superconductors. However, in many high-$T_{c}$ compounds, superconductivity appears near a putative magnetic quantum critical point, suggesting that quantum fluctuations, which suppress coherent electronic spectral weight, may also promote unconventional pairing. Here we investigate theoretically the impact of disorder on such a quantum critical pairing state, considering the coupling of impurities both to the low-energy electronic states and to the pairing interaction itself. We find a significant reduction in the suppression rate of $T_{c}$ with disorder near the magnetic quantum critical point, shedding new light on the nature of unconventional superconductivity in correlated materials.