Critical local moment fluctuations and enhanced pairing correlations in a cluster Anderson model

TL;DR

This study investigates a two-impurity Anderson model near a Kondo-destruction quantum critical point, revealing critical local moment fluctuations that significantly enhance pairing correlations, offering insights into unconventional superconductivity.

Contribution

It uncovers a novel quantum critical point with critical local moment fluctuations that strongly boost singlet pairing susceptibility in a cluster Anderson model.

Findings

Identification of a new QCP with Kondo destruction features

Enhanced singlet pairing susceptibility near the QCP

Insights into superconductivity mechanisms in quantum critical metals

Abstract

The appearance of unconventional superconductivity near heavy-fermion quantum critical points (QCPs) motivates investigation of pairing correlations close to a ``beyond Landau'' Kondo-destruction QCP. We focus on a two-Anderson-impurity cluster in which Kondo destruction is induced by a pseudogap in the conduction-electron density of states. Analysis via continuous-time quantum Monte-Carlo and the numerical renormalization group reveals a previously unstudied QCP that both displays the critical-local moment fluctuations characteristic of Kondo destruction and leads to a strongly enhanced singlet-pairing susceptibility. Our results provide new insights into the mechanism for superconductivity in quantum critical metals.