Possible strain induced Mott gap collapse in 1T-TaS$_2$

TL;DR

This paper explores how strain can induce a Mott insulator-metal transition in 1T-TaS$_2$, revealing a new method to control electronic phases and potentially design switchable devices.

Contribution

It introduces strain as a novel tuning parameter for inducing Mott gap collapse in 1T-TaS$_2$, demonstrating a smooth transition from insulating to metallic states.

Findings

Strain induces a mosaic state with varied electronic densities.

A smooth evolution from Mott insulator to metal is observed.

Strain engineering can enable controllable electronic phase transitions.

Abstract

Tuning the electronic properties of a matter is of fundamental interest in scientific research as well as in applications. Recently, the Mott insulator-metal transition has been reported in a pristine layered transition metal dichalcogenides 1T-TaS$_2$, with the transition triggered by an optical excitation, a gate controlled intercalation, or a voltage pulse. However, the sudden insulator-metal transition hinders an exploration of how the transition evolves. Here, we report the strain as a possible new tuning parameter to induce Mott gap collapse in 1T-TaS$_2$. In a strain-rich area, we find a mosaic state with distinct electronic density of states within different domains. In a corrugated surface, we further observe and analyze a smooth evolution from a Mott gap state to a metallic state. Our results shed new lights on the understanding of the insulator-metal transition and promote a controllable strain engineering on the design of switching devices in the future.