Interplay between charge correlations and superconductivity across the superconducting domes of CsV$_{3}$Sb$_{5-x}$Sn$_x$

TL;DR

This study explores how charge correlations evolve and influence superconductivity in CsV$_3$Sb$_5$ as hole doping suppresses different charge density wave states, revealing their essential role in the superconducting domes.

Contribution

It provides a detailed analysis of charge correlation evolution across doping levels and introduces a multidomain model explaining local symmetry breaking in the second superconducting dome.

Findings

Suppression of metastable CDW coincides with reduced superconducting fluctuations.

Long-range CDW order is suppressed, leaving short-range correlations.

Charge correlations vanish as superconductivity emerges with doping.

Abstract

The kagome metal CsV$_3$Sb$_5$ shows an unconventional interplay between charge density wave (CDW) order and superconductivity. Tuning the band filling is known to rapidly suppress long-range CDW order and drive the formation of two superconducting ``domes" upon increasing hole concentration. Here we determine the detailed evolution of charge correlations across this phase diagram and resolve their interplay with the superconducting state. Upon light hole-doping, the suppression of a metastable $2\times 2\times 4$ CDW state coincides with the suppression of superconducting fluctuations present in the parent CsV$_3$Sb$_5$ compound. Continued doping suppresses long-range $2\times 2\times 2$ CDW order, leaving remnant short-range, quasi-1D correlations that persist across the second superconducting dome. These higher temperature charge correlations are seemingly essential to the lower temperature superconducting state, as charge correlations vanish coincident with superconductivity as a function of hole-doping. A multidomain model of short-range V-V dimer formation within the kagome plane is proposed in the second superconducting dome, where rotational and translational symmetry remain locally broken even in the absence of long-range CDW order.