Point-contact tunneling spectroscopy measurement of Cu$_x$TiSe$_2$: disorder-enhanced Coulomb effects

TL;DR

This study uses point-contact tunneling spectroscopy to investigate how disorder enhances Coulomb interactions in Cu$_x$TiSe$_2$, revealing a correlation gap linked to resistivity and estimating the clean limit transition temperature.

Contribution

It provides the first detailed tunneling measurements on Cu$_x$TiSe$_2$ showing disorder-induced Coulomb effects and relates the correlation gap to resistivity and $T_c$.

Findings

Suppression in density of states around zero-bias due to Coulomb interactions.

Correlation gap size correlates with zero-temperature resistivity.

Estimated clean limit $T_{c0}$ is close to observed $T_c$.

Abstract

We performed point-contact spectroscopy tunneling measurements on Cu$_x$TiSe$_2$ bulk with $x=0.02$ and $0.06$ at temperatures ranging from $T=4-40$ K and observe a suppression in the density of states around zero-bias that we attribute to enhanced Coulomb interactions due to disorder. We find that the correlation gap associated with this suppression is related to the zero-temperature resistivity. We use our results to estimate the disorder-free transition temperature and find that the clean limit $T_{c0}$ is close to the experimentally observed $T_c$.