Incommensurate charge-stripe correlations in the kagome superconductor CsV$_3$Sb$_{5-x}$Sn$_x$

TL;DR

This study investigates how charge correlations evolve in the kagome superconductor CsV$_3$Sb$_5$ with doping, revealing incommensurate charge correlations and electronic symmetry breaking that suggest complex competing charge instabilities.

Contribution

It uncovers the emergence of incommensurate, quasi-1D charge correlations and electronic symmetry breaking in CsV$_3$Sb$_5$, expanding understanding of charge dynamics in kagome superconductors.

Findings

Charge correlations become short-ranged with hole-doping.

Incommensurate charge correlations stabilize beyond the superconducting dome.

Electronic rotational symmetry breaking is observed independently of the charge density wave state.

Abstract

We track the evolution of charge correlations in the kagome superconductor CsV$_3$Sb$_5$ as its parent, long-ranged charge density order is destabilized. Upon hole-doping doping, interlayer charge correlations rapidly become short-ranged and their periodicity is reduced by half along the interlayer direction. Beyond the peak of the first superconducting dome, the parent charge density wave state vanishes and incommensurate, quasi-1D charge correlations are stabilized in its place. These competing, unidirectional charge correlations demonstrate an inherent electronic rotational symmetry breaking in CsV$_3$Sb$_5$, independent of the parent charge density wave state and reveal a complex landscape of charge correlations across the electronic phase diagram of this class of kagome superconductors. Our data suggest an inherent 2$k_f$ charge instability and the phenomenology of competing charge instabilities is reminiscent of what has been noted across several classes of unconventional superconductors.