Ultrafast Mid-Infrared Nanoscopy of Strained Vanadium Dioxide Nanobeams

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Vanadium dioxide (VO2) is a correlated electron material known for its insulator-to-metal phase transition near room temperature.
• Strain engineering in VO2 influences its phase diagram and can create nanoscale phase heterogeneity.
• Previous studies have not investigated the ultrafast transition dynamics at the nanoscale of strained VO2.

Purpose of the Study:

• To investigate the ultrafast dynamics of strained VO2 nanobeams at the 10 nm scale.
• To explore the correlation between local steady-state properties and ultrafast photoresponse.
• To assess the potential for tailoring VO2's photoresponse for device applications.

Main Methods:

• Ultrafast near-field microscopy in the mid-infrared.
• Study of individual, strained VO2 nanobeams.
• Analysis of local switching susceptibility and photoexcitation response.

Main Results:

• A novel correlation was observed between local steady-state switching susceptibility and the local ultrafast response to sub-threshold photoexcitation.
• The nanoscale spatial symmetry of the VO2 transition was found to be breakable by strain.
• Insulating and metallic nanodomains exhibited quasiperiodic ordering.

Conclusions:

• Strain can be used to tune the local photoresponse of VO2.
• Tailoring the photoresponse of strained VO2 nanostructures could enable new ultrafast nano-optical devices.
• This research opens avenues for advanced nanophotonics and optoelectronics.