Evolution of charge correlations in the hole-doped kagome superconductor CsV$_{3-x}$Ti$_x$Sb$_5$

TL;DR

This study investigates how hole doping via Ti substitution affects charge correlations and superconductivity in the kagome superconductor CsV$_{3-x}$Ti$_x$Sb$_5$, revealing evolving charge order and differences from other doping methods.

Contribution

It provides new insights into the evolution of charge correlations and their relationship with superconductivity under hole doping in CsV$_{3-x}$Ti$_x$Sb$_5$.

Findings

Charge correlations evolve from competing supercells in the first dome to no detectable correlations in the second.

Superconductivity remains conventional and unchanged across the phase diagram.

Differences are observed between hole doping via Ti substitution and other dopants like Sn.

Abstract

The interplay between superconductivity and charge correlations in the kagome metal CsV$_3$Sb$_5$ can be tuned by external perturbations such as doping or pressure. Here we present a study of charge correlations and superconductivity upon hole doping via Ti substitution on the V kagome sites in CsV$_{3-x}$Ti$_x$Sb$_5$ via synchrotron x-ray diffraction and scanning SQUID measurements. While the superconducting phase, as viewed via the vortex structure, remains conventional and unchanged across the phase diagram, the nature of charge correlations evolves as a function of hole-doping from the first superconducting dome into the second superconducting dome. For Ti doping in the first superconducting dome, competing $2\times 2 \times 2$ and $2\times 2 \times 4$ supercells form within the charge density wave state and are suppressed rapidly with carrier substitution. In the second superconducting dome, no charge correlations are detected. Comparing these results to those observed for CsV$_3$Sb$_{5-x}$Sn$_x$ suggests important differences between hole doping via chemical substitution on the V and Sb sites, particularly in the disorder potential associated with each dopant.