  Optical properties of refractory intermetallic thin films of Au$_{3}$Zr were
experimentally investigated for the first time, which show distinctive
plasmonic properties in the visible and near infrared region. The films were
fabricated through DC magnetron sputtering at various deposition temperature
ranging from room temperature to 427$^{o}$C and annealed at different vacuum
levels. Both the structural and optical properties are found to be critically
dependent on deposition temperature and anneal conditions. Films deposited
between 205-320$^{o}$C are shown to exhibit lower negative permittivity and
better thermal stability, which could be linked to specific crystalline
orientations. The films are stable when annealed at 10$^{-8}$ Torr, but are
partially oxidized when annealed at 10$^{-6}$ Torr, suggesting oxidization
could be a restricting issue for high-temperature applications in ambient
environment.
