Influence of domain walls in the incommensurate charge density wave state of Cu intercalated 1$T$-TiSe$_2$

TL;DR

This study uses scanning tunneling microscopy to compare charge density wave states in pristine and Cu-intercalated TiSe2, revealing how domain walls influence electronic properties and potentially superconductivity.

Contribution

It provides detailed real-space imaging of incommensurate CDW and domain walls in Cu-intercalated TiSe2, highlighting their role in electronic behavior and CDW formation mechanisms.

Findings

Pristine TiSe2 exhibits long-range commensurate CDW order.

Cu-intercalation induces incommensurate CDW with domain walls.

Domain walls host extra fermions near the Fermi level, possibly linked to superconductivity.

Abstract

We report a low-temperature scanning tunneling microscopy study of the charge density wave (CDW) order in 1$T$-TiSe$_2$ and Cu$_{0.08}$TiSe$_2$. In pristine 1$T$-TiSe$_2$ we observe a long-range coherent commensurate CDW (C-CDW) order. In contrast, Cu$_{0.08}$TiSe$_{2}$ displays an incommensurate CDW (I-CDW) phase with localized C-CDW domains separated by domain walls. Density of states measurements indicate that the domain walls host an extra population of fermions near the Fermi level which may play a role in the emergence of superconductivity in this system. Fourier transform scanning tunneling spectroscopy studies suggest that the dominant mechanism for CDW formation in the I-CDW phase may be electron-phonon coupling.