Observation of First-Order Metal-Insulator Transition without Structural Phase Transition in VO_2

TL;DR

This study reports the first observation of a first-order metal-insulator transition in VO_2 induced by an electric field without accompanying structural change, highlighting a purely electronic transition mechanism.

Contribution

It demonstrates an electric-field-induced MIT in VO_2 without structural phase transition, revealing a non-structural electronic transition in a Mott insulator.

Findings

Abrupt current jump at critical electric field

No change in Raman-active mode frequency during MIT

Structural MIT occurs secondarily to electronic transition

Abstract

An abrupt first-order metal-insulator transition (MIT) without structural phase transition is first observed by current-voltage measurements and micro-Raman scattering experiments, when a DC electric field is applied to a Mott insulator VO_2 based two-terminal device. An abrupt current jump is measured at a critical electric field. The Raman-shift frequency and the bandwidth of the most predominant Raman-active A_g mode, excited by the electric field, do not change through the abrupt MIT, while, they, excited by temperature, pronouncedly soften and damp (structural MIT), respectively. This structural MIT is found to occur secondarily.