Proliferation of metallic domains caused by inhomogeneous heating near the electrically-driven transition in VO$_2$ nanobeams

TL;DR

This study reveals that inhomogeneous Joule heating causes phase inhomogeneities leading to the insulator-metal transition in VO$_2$ nanobeams, emphasizing the role of thermal effects over electric field-induced mechanisms.

Contribution

It demonstrates that non-uniform Joule heating, not electric field alone, drives the transition in VO$_2$ nanobeams, using harmonic analysis and transport measurements.

Findings

Non-uniform Joule heating causes phase inhomogeneities.

Electric field alone does not induce the transition.

Percolation effects influence the transition process.

Abstract

We discuss the mechanisms behind the electrically driven insulator-metal transition in single crystalline VO$_2$ nanobeams. Our DC and AC transport measurements and the versatile harmonic analysis method employed show that non-uniform Joule heating causes phase inhomogeneities to develop within the nanobeam and is responsible for driving the transition in VO$_{2}$. A Poole-Frenkel like purely electric field induced transition is found to be absent and the role of percolation near and away from the electrically driven transition in VO$_{2}$ is also identified. The results and the harmonic analysis can be generalized to many strongly correlated materials that exhibit electrically driven transitions.