Evolution from three-dimensional charge density wave to one-dimensional stripe order in CsV$_{3-x}$Ti$_x$Sb$_5$

TL;DR

This study reveals how charge density wave order in CsV$_{3-x}$Ti$_x$Sb$_5$ evolves from three-dimensional to one-dimensional as Ti doping increases, providing insights into the interplay between CDW and superconductivity in kagome metals.

Contribution

It demonstrates the dimensional evolution of CDW order with Ti substitution using XRD and STM, highlighting the suppression and transformation of CDW in a kagome superconductor.

Findings

Infinitesimal Ti doping suppresses 3D CDW in CsV$_{3-x}$Ti$_x$Sb$_5$

Further Ti doping reduces remaining CDW to quasi-2D order

Emergence of quasi-1D CDW with short correlation length at x=0.2

Abstract

Understanding intertwined phases near quantum criticality is a central challenge in correlated electron systems. The kagome metal CsV$_{3-x}$Ti$_x$Sb$_5$ provides a fertile platform to investigate the interplay between charge-density-wave (CDW) and superconductivity. Here, combining x-ray diffraction (XRD) and scanning tunneling microscopy (STM), we uncover a dimensional evolution of the CDW upon Ti substitution. We find that even infinitesimal Ti doping (x = 0.009) completely suppresses the three-dimensional 2 $\times$ 2 $\times$ 4 CDW present in pristine CsV3Sb5, while reducing the remaining 2 $\times$ 2 $\times$ 2 CDW to a quasi-two-dimensional order. With further Ti substitution, although no CDW transition is discernible in resistivity measurements, our XRD and STM data reveal the emergence of a (quasi-)one-dimensional CDW with a short correlation length of $\sim$ 20 $\AA$ at x = 0.2. The stripelike CDW undergoes a continuous second-order phase transition, characterized by a gradual increase in intensity and correlation length below $\sim$ 56 K. Our results elucidate the dimensional evolution of CDW order in CsV$_{3-x}$Ti$_x$Sb$_5$ and provide new insight into understanding the unconventional CDWs and their role in kagome superconductors.