Appearance of a Domain Structure and its Electronic states in Iron Doped 1$T$-TaS$_2$ Observed using Scanning Tunneling Microscopy and Spectroscopy

TL;DR

This study uses STM/STS to reveal a novel domain structure in iron-doped 1$T$-TaS$_2$, linking the emergence of domain walls to the suppression of the Mott state and the onset of superconductivity.

Contribution

It demonstrates the formation of a domain structure in iron-doped 1$T$-TaS$_2$ and connects domain wall proliferation to superconductivity.

Findings

Domain structure appears in Ta$_{0.99}$Fe$_{0.01}$S$_2$ with suppressed Mott transition.

Increase in domain walls correlates with the emergence of superconductivity.

Domain walls are likely responsible for superconductivity in the doped material.

Abstract

In this paper, we report on scanning tunneling microscopy and spectroscopy (STM/STS) measurements on iron doped 1$T$-Ta$_{1-x}$Fe$_x$S$_2$. A novel domain structure composed of the domains with localized nature divided by the walls is observed in Ta$_{0.99}$Fe$_{0.01}$S$_2$, where the Mott transition is completely suppressed. This indicates that the melting of the Mott state accompanies the appearance of the domain structure. Since the number of walls increase in superconducting Ta$_{0.98}$Fe$_{0.02}$S$_2$, the domain walls seem to be responsible for superconductivity in iron doped 1$T$-TaS$_2$.