Enhanced Transition-Temperature Reduction in a Half-Sphere Au/VO2 Core-Shell Structure: Local Plasmonics versus Induced Stress and Percolation Effects

Abstract

VO${}_{2}$, with its reversible metal-insulator transition accompanied by drastic change in optical properties, is a promising material for numerous applications, including energy-saving smart windows. The transition occurs near 68 \ifmmode^\circ\else\textdegree\fi{}C, which is too high for building-type applications, but this temperature can be tuned by varying the Au core size in Au/VO${}_{2}$ core-shell nanoparticles---and the physical mechanism is a bit unexpected. This research points the way to optimizaton of this thermochromic material for switching devices, optical waveguides and limiters, sensing components, tunable metamaterials, and smart windows.