Role of defects in the phase transition of VO ₂ nanoparticles probed by plasmon resonance spectroscopy

Defects are known to affect nanoscale phase transitions, but their specific role in the metal-to-insulator transition in VO ₂ has remained elusive. By combining plasmon resonance nanospectroscopy with density functional calculations, we correlate decreased phase-transition energy with oxygen vacancies created by strain at grain boundaries. By measuring the degree of metallization in the lithographically defined VO ₂ nanoparticles, we find that hysteresis width narrows with increasing size, thus illustrating the potential for domain boundary engineering in phase-changing nanostructures.