Direct in-situ observation of structural transition driven actuation in VO2 utilizing electron transparent cantilevers

TL;DR

This study visualizes and quantifies the actuation caused by structural phase transitions in VO2 nanostructures using in-situ electron imaging, linking nanoscale motion to macroscopic stress and electrical properties.

Contribution

It provides the first direct in-situ visualization of structural transition-driven actuation in VO2 nanostructures using electron transparent cantilevers.

Findings

Reversible cantilever motion due to phase transition

Correlation of nanoscale deflections with stress and electrical conduction

Visualization of lattice dynamics across length scales

Abstract

Direct imaging and quantification of actuation in nanostructures that undergo structural phase transitions could advance our understanding of collective phenomena in the solid state. Here, we demonstrate visualization of structural phase transition induced actuation in a model correlated insulator vanadium dioxide by in-situ Fresnel contrast imaging of electron transparent cantilevers. We quantify abrupt, reversible cantilever motion occurring due to the stress relaxation across the structural transition from monoclinic to tetragonal phase with increasing temperature. Deflections measured in such nanoscale cantilevers can be directly correlated with macroscopic stress measurements by wafer curvature studies as well as temperature dependent electrical conduction allowing one to interrogate lattice dynamics across length scales.