Electric pulse induced electronic patchwork in the Mott insulator GaTa$_{4}$Se$_{8}$

TL;DR

This study uses scanning tunneling microscopy and spectroscopy to investigate the electronic and structural changes in GaTa$_{4}$Se$_{8}$ during electric field-induced insulator-to-metal transition, revealing complex nanoscale patterns and strong electron-lattice coupling.

Contribution

It provides detailed nanoscale insights into the electronic patchwork and lattice effects associated with the electric field-induced transition in a Mott insulator.

Findings

Pristine samples are homogeneous insulators.

Transited samples show metallic and super-insulating patches.

Local electric fields can trigger the transition at room temperature.

Abstract

Following a recent discovery of the Insulator-to-Metal Transition induced by electric field in GaTa$_{4}$Se$_{8}$, we performed a detailed Scanning Tunneling Microscopy/Spectroscopy study of both pristine (insulating) and transited (conducting) crystals of this narrow gap Mott insulator. The spectroscopic maps show that pristine samples are spatially homogeneous insulators while the transited samples reveal at nanometer scale a complex electronic pattern that consists of metallic and super-insulating patches immersed in the pristine insulating matrix. Surprisingly, both kinds of patches are accompanied by a strong local topographic inflation, thus evidencing for a strong electron-lattice coupling involved in this metal-insulator transition. Finally, using a strong electric field generated across the STM tunneling junction, we demonstrate the possibility to trig the metal-insulator transition locally even at room temperature.