Extraordinary Dynamic Mechanical Response of Vanadium
Dioxide Nanowires around the Insulator to Metal Phase Transition
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Abstract
Nanomechanical resonators provide
a compelling platform to investigate
and exploit phase transitions coupled to mechanical degrees of freedom
because resonator frequencies and quality factors are exquisitely
sensitive to changes in state, particularly for discontinuous changes
accompanying a first-order phase transition. Correlated scanning fiber-optic
interferometry and dual-beam Raman spectroscopy were used to investigate
mechanical fluctuations of vanadium dioxide (VO<sub>2</sub>) nanowires
across the first order insulator to metal transition. Unusually large
and controllable changes in resonator frequency were observed due
to the influences of domain wall motion and anomalous phonon softening
on the effective modulus. In addition, extraordinary static and dynamic
displacements were generated by local strain gradients, suggesting
new classes of sensors and nanoelectromechanical devices with programmable
discrete outputs as a function of continuous inputs