Nanoscale manipulation of the Mott insulating state coupled to charge order in 1T-TaS2

TL;DR

This paper demonstrates nanoscale control of the Mott insulating state in 1T-TaS2 using an electron pulse, revealing a new correlated metallic phase with potential for nanoscale electronic devices.

Contribution

It introduces a method to manipulate the Mott insulating state at the nanoscale, uncovering a novel correlated metallic phase induced by electron pulse treatment.

Findings

Local electron pulses switch insulating to metallic phase.

The metallic phase shows coherent features at the Fermi energy.

The phase transition involves moderate reduction of electron correlation.

Abstract

Quantum states of strongly correlated electrons are of prime importance to understand exotic properties of condensed matter systems and the controllability over those states promises unique electronic devices such as a Mott memory. As a recent example, a ultrafast switching device was demonstrated using the transition between the correlated Mott insulating state and a hidden-order metallic state of a layered transition metal dichalcogenides 1T-TaS2. However, the origin of the hidden metallic state was not clear and only the macroscopic switching by laser pulse and carrier injection was reported. Here, we demonstrate the nanoscale manipulation of the Mott insulating state of 1T-TaS2. The electron pulse from a scanning tunneling microscope switches the insulating phase locally into a metallic phase which is textured with irregular domain walls in the charge density wave (CDW) order inherent to this Mott state. The metallic state is a novel correlated phase near the Mott criticality with a coherent feature at the Fermi energy, which is induced by the moderate reduction of electron correlation due to the decoherence in CDW. This work paves the avenue toward novel nanoscale electronic devices based on correlated electrons.