Spatially anisotropic Kondo resonance coupled with the superconducting gap in a kagome metal

TL;DR

This study reveals how introducing magnetic impurities into a kagome superconductor induces anisotropic Kondo resonances that interact with and enhance superconductivity, providing insights into magnetism-superconductivity interplay.

Contribution

It demonstrates the emergence of anisotropic Kondo resonances around Cr impurities in CsV3Sb5, breaking symmetries and affecting superconducting properties.

Findings

Kondo resonances form ripple-like patterns around Cr atoms.

Superconducting gap and coherence peaks are enhanced with Kondo screening.

Magnetic impurities weaken charge density wave order and participate in Kondo effect.

Abstract

The chromium-based kagome metal CsCr3Sb5 has garnered significant interest due to its strong electron correlations, intertwined orders and potential for unconventional superconductivity under high pressure. The evolution of magnetic and superconducting interactions as the more frequently studied CsV3Sb5 is doped to CsCr3Sb5 remains poorly understood. Here, we demonstrate the emergence of a spatially anisotropic Kondo resonance intertwined with the superconducting gap, enabled by introducing magnetic Cr impurities into the kagome superconductor CsV3Sb5. The addition of dilute Cr impurities not only weakens long range charge density wave order but also produces local magnetic moments that leads to Kondo resonances. We show that the Kondo resonance forms anisotropic, ripple like spatial patterns around individual Cr atoms, breaking all local mirror symmetries. We further reveal that with the emergence of Kondo screening, the coherence peak and depth of superconducting gap with finite zero-energy conductance are enhanced. This suggests that non superconducting carriers at the Fermi surface in the parent compound participate in the Kondo effect, simultaneously screening Cr magnetic moments and increasing the superfluid density. Our findings offer an opportunity to study the interplay between superconductivity and local magnetism in kagome materials.